Defense tactics

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Getting attacked, whether by tribals, pirates or hordes of angry animals is a common event in the rimworlds. Defense against these attacks is one of the keys to having a successful colony.

This page details different tactics for defense and visualizations of them, applicable to most stages of the game.

Raiders

Behavior

Raiders will attack randomly chosen constructed objects, colonists and colony animals. They will not attack natural rock walls (not the case for sappers), non-hostile wild animals or unpowered turrets. They will also attack prisoners if they are captured from their enemy factions.

They usually set fire to crops in growing zones, power generation or conduits, and other production buildings. They will melee attack furniture, doors and walls. They also use thrown explosives on structures, and some use EMP grenades to stun your turrets.

Raiders will prioritise firing on colonists or turrets that are actively engaging, but will otherwise attack random objects, meaning you can put doors or walls near your defenses to temporarily distract them.

Preparation

Humanlike raiders will sometimes start by standing around in a group where they spawned and will continue this until they see a colonist nearby or they hit a certain preparation time limit, at which point they begin the assault. Because a colonist can set them off early, you can plan out the time you want them to attack.

Equipment

Raiders spawn with randomized equipment depending on their weapon and clothing budget and their raider type.

Apparel

Pirates can range from only wearing a tattered pair of pants to armor vests to full sets of power armor. Mercenary slashers will always come in shield belts and only they do so.
Tribals always come in tribalwear, with some in war masks or war veils.

In cold environments, both will come in wearing parkas or tuques, protecting them from temperatures of around -40 to -50°C, sometimes up to -110°C if they wear wool parkas. They don't usually come in wearing dusters or cowboy hats in hot areas, making them vulnerable to the heat.

They tend to wear leather, cloth or synthread clothes, which don't provide good protection, and less commonly the more protective devilstrand or hyperweave.

While mid-late game pirates usually come with around 30% - 40% sharp protection, with quality apparel you can push yours to have more than 70%, giving you the upper hand.

Weapons

Pirates spawn with most weapons in the game, whatever their faction is willing to provide them.
Tribals usually come equipped with primitive weapons, but can sometimes be seen with captured high-quality melee weapons as well.

Weapons are assigned at random, meaning that more often than not raiders don't get to use a weapon appropriate for their skills; brawlers can often be seen charging into battle with a gun and a -20 mood penalty, supported by skilled shooters which try to shoot with a melee weapon before giving up and charging in.
However, some classes of raider always come with the same (category of) weapon. For example, mercenary snipers always use sniper rifles, grenadiers wield some form of thrown explosive and tribal archers always use neolithic ranged weaponry.

If you have your colonists equip suitable weapons according to their skills, you already have an advantage over the raiders over this point.

Drugs

Pirates or Outlanders may utilize some form of combat-enhancing drug, namely go-juice, yayo and luciferium. They will usually start off addicted to them, and will carry some in their inventory which is dropped upon death. They may also use multiple drugs, disregarding the risk of overdose.

These can reduce the amount of the pain received, making the raider last longer in battle before going down. Increased movement speed also allow raiders to get into position earlier, and brawlers to harass your defenders more easily.

  • Go-juice is an excellent combat drug that makes the raider much more efficient in battle. It eliminates 90% of pain, gives a 30% movement speed buff, and a 10% consciousness buff for more accuracy. The raider is almost guaranteed to fight until death, or the rarer case of incapacitation through a shattered spine, severe brain damage or removal of both legs.
    • It's almost always more worth it to use body part-destroying weapons such as the Sniper rifle to kill them, as Go-juice does not reduce the actual damage they take.
  • Yayo grants a 15% buff to speed and eliminates half of pain received. Enemies under the effect of yayo are more durable against damage not concentrated on a vital body part
    • It will take more hits to down them, and more likely the raider dies first due to lethal damage, but is still possible.
  • Luciferium grants a wide range of buffs to the user, from increased organ function, to slight movement speed and consciousness buffs, to reduced pain.
    • It's more troublesome to capture addicted raiders since you'll need to regularly feed them luciferium to sustain their lives, which is very expensive and hard to come by -- it's usually more worthwhile to just strip and finish them on the spot.

Battle tactics

You can face off your opponents by employing a variety of clever tactics.

Flanking and Surrounding

To flank enemies, have some defenders approach enemies from the sides or the back instead of concentrating fire on the front. To surround them, attack from all sides.

Enemy ranged units often stay in the same spot when engaging your colonists, and they tend to have effective cover facing one direction only, making them vulnerable to flanking. Flanking enemy ranged units can distract them and cause them to lose their cover advantage with attacks coming from multiple sides. While this makes you lose the advantage of high-quality cover, it is balanced out by the enemy's loss of cover.

This works best against entrenched ranged enemies attacking you from one side. They should be occupied with attacking frontal targets so you can creep up to them to unload lead on them from another angle. It's even better if you pair with melee to tie them up, buying time for your soldiers to get into position and preventing them from moving into new positions.

Rounding up any fleeing survivors also becomes easier if you have someone (especially melee fighters) blocking off escapes from behind.

Moving in

While moving in you need to make sure you stay far enough away from enemies, and directly right-clicking on the destination will nearly always result in a path that crosses with the enemy.

This can be overcome by shift-clicking to form a path for the pawn to follow, making sure to keep sufficient distance.

Shield belts, drawing enemy fire from a different direction, or simply using walls and terrain to block projectiles are all good ways to move in.

Wide arc flank

This tactic is about scattering your fighters in a wide arc facing your enemies. Rather than huddling together behind continuous lines of cover such as lines of rock chunks, each soldier should be taking cover on their own, and be able to shoot straight at the enemy without anyone else in between.

This gives more flexibility in positioning as well as greatly reduced vulnerability against explosives or collateral damage. Engaging your flankers also results in enemy fire being scattered, so focus fire won't take down anyone easily.

You can deploy shielded colonists to draw fire effectively from your gunners, though they need to be arranged carefully so as to be able to tank without taking friendly fire.

Perfect against preparation raids or in-construction siege camps when you can't use your static cover and they won't directly attack your base upon arrival. However if the enemy has a significant cover advantage (such as sandbags) then this tactic may not work out in your favor.

Spacing out

Each colonist should ideally stand 1 tile away from other colonists, thus negating the chance of enemy bullets hitting somebody else after missing the original target, which deals a lot of damage to static grouped up defenders.

Explosives will also hit fewer people this way, though there are better countermeasures than simply spacing defenders apart.

If you have enough space, you can arrange colonists to stand 3 tiles away from each other. That way, crowd control weapons such as miniguns or heavy charge blasters can't hit at all.

Melee tactics

Melee soldiers are a useful asset in your colonies, if used correctly. They can bring disruption against ranged enemies, or fight off invading brawlers charging into your lines.

Ranged attackers shooting behind cover from a distance could be a pain to deal with for your own ranged forces, while melee attackers can get close enough to deal heavy damage to the ranged defenders.

It's best to equip your melee colonists with Shield belts and good armor to protect against heavy fire from both sides and distract the ranged attackers. Melee attackers without the protection of shields are highly vulnerable to gunfire, even if heavily armored. Before battle, hide your melee attackers so that they remain hidden until all enemy melee attackers are engaged in battle, or put them in line in front of your gunners for quick deployment and damage absorption.

Friendly fire is a serious issue in hand-to-hand combat, as you can easily hit your own fighters.

Melee sortie

This tactic involves using a small element of melee colonists to ambush enemy ranged attackers and take the heat off your own gunners.

Sending groups of melee attackers against enemy shooters can cause great disruption, because being engaged in melee interrupts ranged attacks, prevents further attacks from occurring and lowers movement speed drastically. It can be used to take down annoying long-ranged snipers or small gunner groups, as when forced into melee they can only fight back with makeshift melee attacks with their guns, which are woefully inadequate against a dedicated brawler.

Charging at entrenched ranged attackers also diverts their attention from your own entrenched forces to your charging brawlers.

Melee rush

Melee rushing is the tactic of sending your melee attackers to engage hostiles all at once, rather than focusing on shooting them down or sending small parties to take down troublesome enemies.

Melee rushes can work alone, especially with quality equipment; well-equipped melee rushes can hold off an attack and cause raiders to flee despite being slightly outnumbered. They also attract a great deal of friendly fire from the pirates, as they try to shoot down your brawlers, hitting their allies in the process.

If you aren't afraid of friendly fire, it can be combined with a firing squad from a distance for devastating effects. The brawlers cause chaos within the raiding party while the firing squad lays fire to destroy them while the raiders are trying to cope with your brawlers.

Peeling

If a vulnerable gunner is under attack by melee attackers, you can 'peel' them away using your brawlers. Have them engage the melee attackers, who will then focus on your brawlers, allowing your gunner to get to relative safety.

Trained animals automatically peel for their assigned masters, if 'Release animals' is Off. The animals will attack any hostiles coming close rather than straying off to attack distant targets.
Setting 'Release animals' to On right when a colonist in distress near the trainer causes the animals to swarm the attacker, peeling them off.

Peeling is a relatively high-risk activity, as you are trying to put a pawn at risk in return for allowing a pawn at greater risk to escape. Peeling pawns should be expendable or decently armored.

Self-defense

Some guns deal more damage than melee at point-blank. Others still hurt in melee, even surpassing some low quality melee weapons. This allows shooters to have a fighting chance against melee.

Guns that do better at point-blank can be manually directed to fire at melee range, bypassing shields in the process. If they aren't better at point-blank, stick to melee.

Shooters can fight off small animals quite easily with melee, so have them fight back instead of letting the animal chew them to death.

Should enemy melee brawlers charge in, melee attacks with guns are a viable alternative if your colonists are adept at melee combat as well. Since they don't usually emerge victorious from a 1v1 melee fight unless there is a massive skill gap, have someone else join in the fray, be it a brawler or gunner.

Blocking enemies

You shall not pass.

Enemies can be physically blocked by colonists or animals, denying them access to locations. This can be done to a significant tactical advantage.

Heavily armored soldiers are needed to body block active combatants, as they will take a lot of hits while blocking, and even so they will eventually collapse due to sustained damage. They should also be able to deal heavy damage at point-blank.

Melee blocking

When faced with a full melee attack, instead of engaging enemies on the frontline, retreat behind your walls, and open doors to use as chokepoints. Leave up to three melee brawlers standing right behind the doors to block enemies while cutting them down, while stationing more nearby as replacements, and gunners behind to fire on the intruders. This forces enemies to trickle in and fight with your soldiers one-by-one, making them significantly easier to dispatch of.

This is a horribly effective way to defeat melee attacks. Compared to a regular frontline defense, this tactic significantly reduces the casualties your side will sustain. You also don't need to build anything specially for this purpose- any opening or door in the wall will do.

For maximum pain, use high-DPS guns for your backline for bringing the hurt, combined with quality melee for your frontline to deal sustained damage in between barrages.

Combined with measures to force enemies into close range, it works wonders against ranged enemies as well.

Other uses

Blocking can be used to slow down prison breaks or seal off escape routes for enemies.

Tanking

This tactic simply requires you put your shielded colonists before your static gunners to partially soak up gunfire. This is best when you have insufficient cover, or additional cover to block more bullets for your frontline tanks.

As with any tactic involving meat shields, this poses a great risk to colonists' lives. If the colonists' shields are downed and they are not well-armored, you will have to get them to retreat behind cover until their shields come back online, otherwise your colonist will be exposed to ruthless gunfire.

Beware of high damage-per-hit weapons which can instantly down shields.

Distracting rockets

Rocket launchers are painful to deal with, due to the huge damage they deal to a massive area. In the mid-late game they are one of the biggest threats from the enemy.
The best way to deal with them is to distract them to fire elsewhere, in order to greatly reduce the amount of damage received.

Raiders with rocket launchers are often seen in the backline preparing their rockets, while their allies lay down fire at the front. They get distracted quite easily, wasting them on animals or lone colonists. This can be exploited simply by charging them with melee units, which will cause them to fire it towards them and away from the rest of your forces. They may fire at point-blank, injuring many of his comrades and themselves. If you're fast, you can even intercept them before they can aim their rocket launcher, forcing them into hand-to-hand combat, eventually overwhelming them and yielding the launcher which can be captured for future use.

This is a high-risk but necessary move to take, and some pawns may need to be sacrificed.

You have to make that colonist the only available target for them to consider attacking. If they have a better target with less possible friendly fire, they will attack them instead. To combat this, have all your other units, including animals, stay completely out of range until the rocket launchers have been neutralized.

Shielded unit deployment

Deploy brawlers equipped with shield belts and heavy armor, letting the shields block the blast as well as some gunfire. As soon as all rocketeers have discharged or shields are broken, quickly return to cover. Colonists should keep moving while distracting, especially when facing against triple rocket launchers.

Be prepared to sacrifice someone, as their shields are very likely to be broken whether by the blasts or concentrated gunfire, exposing the colonist within.

Expendable animal charge

Have animals that are both expendable and fast charge the enemy, rocket soldiers included. It's especially good if the animals can survive a rocket blast, as it allows them to continue distracting any further rocket launches or enemy fire.

They do not need to be obedience trained, as you can use animal area zones to force them into areas, however animals have a delay before moving into their assigned zones and may be very far away, so this is less effective when enemies are already charging in.

For multiple rocket launchers, send animals in batches, such as by assigning animals to different handlers and setting them to attack at different times, to prevent them from being wiped out by a single blast.

Friendly fire with rockets

Besides being caught in a blast, enemies can also take friendly fire if the rockets impact them instead of your colonists.

You can increase the chance of this happening by having the rocket travel over as many enemies as possible through aligning your distractors.

Rescue

When a colonist is downed or severely injured, drag them out of the fight immediately. Don't leave them there otherwise they risk dying from stray bullets or blood loss. You don't really need to send them directly to hospital; just drop them off somewhere outside of active combat.

Colonists lying outside cover are riskier to rescue. Choose the right time to pull them out, using your best-protected colonists, and don't let anyone near at other times.

You should have a few rescue members stand near a fight to pull out downed colonists. Non-combatant doctors should be drafted to stand near the medicine storage to allow them to quickly grab medicine for treatment.

Spacing out your forces prevents the downed colonist from receiving further fire until being rescued.

If a colonist cannot reach the hospital in time (~2 hours from death or less), have them immediately lie down at a temporary sleeping spot safely outside the battlefield, then have the doctor closest to the medicine storage go and treat the colonist ASAP. Patch colonists up a little such that they can reach the hospital without bleeding out, then carry them there. You will have a higher infection chance this way, but it's faster than having the doctor carry the colonist into the hospital.

Friendly fire management

Friendly fire is a serious issue when facing close-range attackers, especially manhunter packs. If they manage to run past your barrage of gunfire to engage your ranged soldiers, they may receive more injuries from friendly fire in the ensuing chaos than the attackers themselves. You need to be careful when directing your troops so you don't hit your own forces by accident.

Pawns can fire over the shoulders of friendlies up to 2 tiles (i.e. 1-tile space in between) away, meaning that you can have a 3-wide row of soldiers without friendly fire, which is not recommended.

  1. When the enemy breaks the ranks, only let the soldiers closest to melee attackers fire at them.
    • Manually re-target the others to fire at another direction, repositioning them if needed.
  2. Disable 'Fire at will' when the enemies are closing in so they won't switch targets, potentially causing friendly fire.
  3. Have only 1 line of shooters so stray bullets, including bullets fired horizontally at melee attackers, will less likely hit someone.

Hit and run

Against slow or static targets you can employ this to weaken them. You will need several fast-moving long-ranged colonists, possibly with sniper rifles. Have them move within range to fire, quickly exiting range once the enemy returns fire. Repeat until conditions are no longer safe to conduct this attack, such as enemies entering full aggression and charging.

Effective against siege camps and preparing raiders for they tend to stay put at their location until they are aggravated into attacking.

Kiting

This risky and situational tactic is effective when employed correctly.

It involves the use of fast colonists (with 120-140% or more Moving) running near moving enemies to gain their attention. Then, outrun them with your kiters while always staying within their attention range, if not the enemy will decide to engage other targets instead. After running far enough, fire a few shots at them before running again. This way, kiters can distract a group of enemies by leading them around the map, while chipping away at their health.

As long as your colonist safely outruns hostiles, you're fine. However, if the enemy catches up, your colonist will be slowed and on his own.

Equipment

A fast, long range weapon is safest (e.g. assault rifle), while a fast moderate-range weapon (e.g. machine pistol) may be used but is more risky. Slow weapons such as sniper rifles are not recommended as the need to stand still for extended periods puts soldiers in grave danger.

Kiting colonists should be armored while still maintaining a fast speed.

Firing at cover

While cover works best against attacks coming straight, it's usually better to fire straight at the target instead of from an angle. If you fire straight at it, only 1 unit of cover will be effective, but if you shoot at a diagonal angle, 2 units of cover will be effective, both being capable of blocking shots, in total contributing to a higher cover effectiveness.

However, if you can get to the point where you're almost firing horizontally at the raiders, then cover becomes nearly ineffective at protecting the raider, allowing many more shots to connect. This often requires you get out of your own cover, so it's not recommended unless you can find suitable cover nearby.

For skilled medium-long range shooters it's best to shoot from a great angle to hit them from the sides.
However for not-so-good or short ranged shooters it's better to directly fire at them instead as the extra distance will make it harder to land hits, or cause the raider to exit firing range.

The below shows the difference firing angle makes on the hit chance of a pawn hiding behind cover. All values from Alpha 16.

Baiting

Faster, more well-protected colonists can be used to lead enemies into traps or ambushes. This is for situations when you have defenses concentrated in one direction, but the enemy comes from another.

Luring in

Enemies can be lured closer to your base by keeping your colonists out of sight, then swarming out to attack once they draw closer to your base.

This can be used to negate the range advantage of enemies.

Animals

The animals on the map, tamed or not, can be used to your advantage.

Raiders never come using tamed animals so the advantage of animals on your side is solely yours.

Tamed animal release

With your handlers, you can amass a huge army of animals to charge the enemy. Simply find a good combat-capable animal, tame it, and train it to learn Release.

There are many animals that are good for this purpose.

  1. Wild boars are an excellent choice as they can graze, reproduce quickly, move fast and pack a punch.
  2. Squirrels are a surprisingly good choice despite their low DPS and health; they are exceedingly fast and small, making them hard to hit, as well as reproduce fast.
  3. If you like bigger animals, you can also tame elephants or rhinos.
  4. Boomrats are a suitable choice of animal if you want an army of suicide bombers.
    • Boomalopes are less effective as they are much slower and easier to hit, despite a much bigger explosion radius and higher melee DPS.

Tamed animals also cause pirates to fire near their allies in a bid to get them off their allies, potentially causing friendly fire.

Meat shield

The animals surrounding a handler can be used as a convenient meat shield as they take bullets, arrows and other projectiles (but not explosions) for their master. Provided they don't stray too far, they won't receive friendly fire as the shooters simply fire over them. All you need is to train Obedience, instead of Release.

Strategic zoning

Raiders take their sweet time to exterminate any trace of your tamed animals on the map. This can be exploited to your advantage, as long as you're willing to have a few animals valiantly sacrifice themselves.

  • Distraction: If you let your animals run all over the place, raiders may be tied up trying to wipe out the animals. This can give your colonists time to prepare, such as entering defensive positions or running to your mortars to fire a few rounds, as well as scatter the raiders making them easier to deal with. Raiders wielding rocket launchers also tend to waste them on your animals, leaving your colonists and structures mostly unharmed. However if they see better targets they will come at them instead.
  • Manipulation: Animals can be moved around without the need of training Release, simply by changing the allowed zone of your animals. A short time later, the animals will move towards the zone and stay there. When animals are sleeping you can put animal sleeping spots beneath them and then remove them to wake them up.
    • Aggressive zoning: Zone animals in a place where you are expecting an encounter with enemies. Enemies will notice the animals and will start attacking, making them fight back and injure or even down the attackers. This method works for any animal, even those that cannot be trained. Remember to undo the zoning otherwise the animals may starve.
    • Animal chokepoint: Zone the animals in a chokepoint, creating a dense cluster.
      • This is vulnerable to AoE weaponry so increase the area of the zone to make it that animals don't get too tightly together.

Aggravating animals

If you have any easily enraged wild animals (wolves, cougars, grizzlies, rhinos, etc) standing near the enemy, you can shoot them to anger them and make them charge at the enemy.

You can also opt to enrage an animal then have a fast colonist (>130% Moving) lead it towards the enemy. Some enemies will stop and engage the animal, potentially causing it to switch targets. For quite the obvious reasons it's best to equip a shield belt on the kiting colonist if he isn't the one enraging the animal.

For this, larger animals are best due to their high health and damage. A thrumbo can be considered a godsend in a raid; just send 1 straight into the raider hordes, and let 'er rip.
Smaller animals are faster and hard to hit, making them decent distraction and causing a hefty amount of friendly fire among the enemy as well.

Remember, if you can down the animal easily with colonists, so can the raiders.

Base scattering

This is a last-ditch tactic to defeat humanlike enemies if you are significantly outnumbered.

Instead of engaging them right away, let enemies scatter around the base first. After they scatter widely apart, divide and conquer, using large groups of soldiers to overcome them with ease, while others are busy demolishing other parts of your base.

Remember to patch up the base after the damage done. Coolers are especially tricky as they serve as weak points and are expensive.

Outside help

If the storyteller is feeling somewhat merciful, outside help may come to save the day.

Don't count on this however, as these rarely happen on their own, and most of the time you still need to fend off the raiders yourself.

Friendly reinforcements

Occasionally while hostiles are on the map, a friendly military caravan will come to bolster your defenses. The threats may also coincide with friendly trade caravans, visitors or passersby, who will help to engage a common enemy.

This requires you be already allied with some factions, so that they will send help of meaningful value; otherwise they may just send a few people who will quickly get downed and serve no purpose other than distraction.

Besides actual assistance, traders may also come with around 550 - 1000 points, enough to hold their own against a smaller raid. This allows you to have decent fire support around half the time, simply by calling in 1 trade caravan every 1 day and 8 hours. While this method costs silver (hence being more expensive), it allows you to trade, as well.

You may also call for additional help at a cost of -20 goodwill. This can be repaired by diplomatic gifts, or rescuing and treating downed friendlies.

Common enemy

If mechanoids, manhunters or another enemy faction show up, raiders may stop to engage them. This causes losses to both groups of enemies, making it easier to pick off the stragglers.

If there are unopened ancient shrines you can open them, which may contain artifacts, mechanoids, confused spacers, all useful against raiders, or none of the above.

Using the psychic animal pulser is essentially invoking this tactic, but you need to be very careful when using it.

Environmental hazards

Very rarely, when unable to put a proper fight, you can count on Mother Nature to play for your side. Invaders will come to you without proper protection against the weather. You will be able to fend off the attack without confrontation.

Choosing to play on an extremely hot or cold map, such as in a sea ice biome near the poles, seals the fate of all raiders foolhardy enough to come.

Humanoid assaults

Sieges

During a siege, raiders go to a location outside your base, receive materials via drop pod and will proceed to build a simple mortar camp. The mortar camp will generally have 2 mortars and sandbags surrounding the mortars facing your base.

When faced with a siege, there are a few strategies you can use.

In most cases it's better to attack the siege camp as the raiders will continuously siege the colony even if you're in hiding, and most likely you will eventually need to face off against the raiders yourself.

Camp assault

If you assault their camp, one possibility is sniping either the shells or the mortars, hoping an explosion kills many of the raiders. If you want to leave those intact, you can snipe the raiders themselves. Keep in mind that killing enough of them prompts them to assault your colony directly instead of continuing their siege. Defeating them early enough will result in most of their items remaining intact, which you can take for yourself.

Unlike most defensive situations, this time they will have the advantage of good cover on their side. You will have to find suitable cover, such as rock chunks, which you can fire from.

Sniping mortars under construction, when they have much lower health, is effective at wasting the enemy's resources.

They are vulnerable to flanking if they haven't finished their sandbags or left a side uncovered. However, once all cover is completed, flanking is less of an effective solution.

Early interception

The best time to attack them is when they've just started building their camp. At this time their resources would have arrived.

Attacking them at this time forces them to use rock chunks just like you do, instead of having the superior sandbags on their side. Their mortars won't be ready as well.

Attack only when their resources have arrived, otherwise they will flee and not send any resources, which you could've stolen had you attacked later.

Hit-and-run

An effective tactic to lure sieging raiders out is to conduct hit-and-run attacks against them. Taking down someone usually causes them to give up on sieges and directly attack, making them lose their cover advantage.

Forced shell extraction

You can extract the shell out of enemies' mortars, even if you haven't claimed them yet. This allows you to shut down enemy mortars simply by extracting the shells over and over again.

Sneak attack

If you don't have the strength to attack directly, you can wait for them to sleep at night, then use the opportunity to set your colonists into position for a sneak attack.

Once someone receives an injury, everybody will wake up, so be sure to have everything in place.

  1. Creep very close to them (no more than 3 tiles away), then unload your guns on the exposed raiders. Nearly every bullet will connect, dealing heavy amounts of damage up front.
    • After being woken up, they will scramble towards the closest source of cover, buying you a few seconds to shoot them or retreat.
  2. Give them a brutal wake-up call by sending brawlers in, beating up dangerous enemies like rocketeers first.
  3. Steal their supplies and wait for them to send more. Free food and mortar shells!
  4. Burn the enemy with fire, a task made much easier while they are off-guard. This will eventually force them out to attack after suffering from heavy losses.
    • Lighting the mortars on fire allows them to be destroyed with ease.
    • Surround the camp with fire. Upon waking up, they will put forward their futile efforts to controlling the raging sea of fire around them, eventually giving up and attacking.

Countering with mortars

If you have your own mortars, you can use them to fire back at the raiders.

High-explosive shells are inaccurate, but can deal heavy damage to tight groups of raiders, ignoring all cover but solid walls in the process. If you're lucky, you can take out some of the raiders, or even the mortars.

Incendiary shells are an effective way of distracting sieges as the raiders will be preoccupied with extinguishing the resultant flames. 2 mortars are usually enough to keep them from doing any activity other than firefighting, unless it is raining or there are no flammables nearby. This deals little damage to them, however.

EMP shells are extremely efficient siege-breakers; they can easily detonate the mortar shells, killing nearby raiders, as well as stun the mortars, preventing them from firing. Sometimes only 1-2 shells are enough to prompt them to attack.

Deep tunneling

Mortars cannot hit anything that is under an overhead mountain. This makes deep mining a effective defensive strategy against heavy bombardment. If you don't build your base into a mountain, you may at least consider digging out at least one panic room for non-combatants to hide within from the shells while others head out for the assault.

Shielded melee charges

Full melee charge at the edge of the map, with everyone shielded and equipped with melee weapons.

Pirates or Outlanders can come with all-melee charges complete with shield belts. This can prove a threat to colonies, especially against ranged-heavy defense forces as they charge towards the colonists directly with their shield belts blocking large amounts of gunfire or trap damage.
While they are vulnerable when their shields are down, many can still reach your colonists and engage them in melee combat.

Melee blocking

The Melee blocking tactic is especially useful here; for better effectiveness, open multiple chokepoints to spread out enemies and keep them busy trying to squeeze in, otherwise they will get bored and wander off to attack other things.

Weapons

  1. High-DPS single-target weapons are optimal in this situation. Focus fire to break down shields and quickly down the exposed enemy.
  2. EMP weapons can be used to devastating effect by knocking out their shields with 1 hit. A lucky hit with an EMP shell can take out most of the shields in a melee raid.
  3. Explosive weapons may be used to break their shields, though they block the entire explosion so a single explosion won't hurt them much. They should be used in conjunction with EMP weapons if you're looking for #damage.
  4. Incendiary weapons penetrate the shield and set the raider on fire, distracting them. While their shields continue to block gunfire, the distraction makes it easier for them to be broken, as well as scatters enemies apart.
  5. Sniper rifles are capable of breaking a weaker shield with a single shot. Combined with their long range, this makes them a good supporting weapon to weaken an incoming charge.
  6. The Firefoam popper is a surprisingly effective option in this situation. In addition to spreading a wide field of foam over the ground that slows down anyone walking over it, the popper will deplete shields, stripping melee attackers of their crucial protection.


Sniper party

Raiders can come using only sniper rifles, giving them very long range.

The danger comes in that if you engage them conventionally, you may need to exit your quality cover, removing your cover advantage.

Luring in

Instead of engaging them on the frontline, you can keep everyone out of line of sight, then rush out only once they get close to your base, negating their ranged advantage.

Explosives assault

Enemies may come in mainly equipped with explosives, such as rocket launchers and grenades. This deals serious damage to both your base and your colonists.

Grenadiers

Most of the enemy will be grenadiers, which have a short range and are vulnerable to fire from a distance. You can shoot these down with concentrated fire quite easily, but make sure to dodge the grenades.

Melee engagement

You can go hardcore and send in all your shielded brawlers to go straight at the enemy rocketeers. Due to a lack of gunners for cover fire, and the fact that grenadiers can't hit moving targets, shielded brawlers should find no difficulty charging deep into the enemy.

The priority target are the rocketeers; make sure that all of them are forced into melee combat before they can fire. If you see that they are about to fire and you can't get into melee range, scatter your brawlers to distract the rockets instead.

However, once engaged grenadiers can now hit your brawlers, so beware. At least now they can also cause heavy friendly fire, as long as you keep the enemy from running away from them.

Base flank

Besides sending one large attack party, enemies can also split up their forces and attack your base from multiple sides. To adequately defend against this sort of attack, you may in turn need to split up your defenses and fight two different battles at once, thus increasing the difficulty.

Sappers

Sappers will mine and blast their way through any obstacles, such as natural or constructed walls, though avoiding high-health ore veins. They will also try to circumvent your defenses to attack from another direction. In an open base, sappers can usually be treated as a normal bunch of raiders. However, they are a great threat to killbox-dependent, mountain or walled bases, or any form of defense that doesn't rely on colonists.

Their grenadiers and miners deal heavy damage to structures; even the toughest plasteel walls will not stop them for long. They will also persistently try to tunnel into your base, continuing even if their digger is killed or the raiding party is under attack.

General strategy

Do not rely on perimeter walls or natural rock walls to hold them off due to their immense damage against structures.

With enough manpower, you can choose to intercept them while they're tunneling into your base. They tend not to use cover when doing so, so you can catch them by surprise. Concentrated fire is devastating in a tunnel, and you can quickly dispatch any diggers, provided you get the jump on them.

If you're in a mountain base you can draft a few melee pawns to wait at the entrance, as well as a few ranged pawns facing the entrance to fire down the tunnel. When they do break in you will already have prepared to face the raiders and can pour a stream of lead right into their face or cut them into pieces.

You can 'funnel' sappers by using turrets placed inside your base; sappers will avoid these, and will go to an area without the turrets. Keep in mind that you will have to kill them by drafting colonists instead of relying on your turrets.

If you have the time and resources, try placing an IED trap right behind the rock wall that a sapper is trying to tunnel through, to catch them by surprise with an explosive blast. This is especially effective if it's placed right on the other side of a loose rock chunk (easily found in tunnels), which will slow down any enemies stepping over it enough that they won't be able to retreat in time.

Hit-and-run interruption

Hit-and-run can be used against sappers very effectively by interrupting their AI, causing them to regroup before digging again. This can be combined with mortars to pound them while they are constantly distracted.

Aftermath

Remember to cover up any tunnels or gaps in your defenses as they open up an opportunity for raiders to come straight into your base. You may fortify it and turn it into a booby-trapped chokepoint to catch unsuspecting raiders seeking direct entry.

Drop pod attacks

Sometimes pirates or mechanoids will come in drop pods. If they land at the edges, they can be treated as a normal raid party, unless you have expanded to the edges, in which they will land inside your base.
To defend against this, have a second line of defenses inside your base so you can deny the drop-podders easy entry into your base.

The main danger comes in landing right in the center of your base. Capable enemies not using alternative strategies such as sieges or sappers have a 10% chance of doing so.

Once they choose to land there, things will get ugly. By landing in the middle, they bypass most of your conventional defenses, and you can't use your cover advantage against them. They will also break through constructed roofs on their way down, landing right inside rooms and buildings. This can put not only your colonists, but your stockpiles in grave danger, as well, especially if they land near your volatile mortar shells or chemfuel stores, or batteries.

Fortunately for you, they have a short delay (520 ticks (8.67 secs) to be exact) before they open and all hell breaks loose. They also come in smaller numbers than regular raids.

Enemies in drop pods cannot land in tiles beneath an Overhead mountain, so tunneling deep underground can make safe rooms.

Strategy

Once you see them land, you should immediately draft any nearby armed colonists to the site, whether they are your designated soldiers or not. Let them hold off the attackers for a while before your soldiers arrive to help. You have less than 9 seconds before they open, not enough for a soldier to get halfway across the map to help.
Any non-combatants should immediately be evacuated. They may still stay close to help in rescue efforts, pulling out any downed colonists. Make sure it's safe to rescue them- as in rescuers not walking through the crossfire and back again to get a colonist to the hospital. You may need to forbid doors to prevent them from walking through the firefight into a hospital.

Melee is useful against these attacks, for you can immediately start beating up the enemy as soon as they exit the pods. They can also shut down dangerous enemies such as rocketeers.

Like other raids, humanoid raiders will attempt to flee after receiving heavy losses; however, if they land inside enclosed areas of your base, they will be trapped, allowing your colonists to down and capture them at leisure. You simply need any blunt weapons or even bare fists; in their panic, they won't try to fight back until you're well into beating them up.

Cover

You should use your furniture or wall corners as cover and fire from behind them. You can also have 2 colonists hiding behind each doorway for full cover. Toggle the doors to be held open, otherwise they can't fire. Be careful as enemies will also utilise cover as well; to combat this, attack from multiple angles or use melee fighters.

Colonists with high construction skill can relocate furniture; use this to your advantage by creating cover for yourself and removing it from enemies.

If you have larger bases, you can built indoor defensive positions along crucial corridors, but take care not to let the enemy use them. Stone shelves are an option as they are durable, non-flammable and beauty-neutral.

In an indoor firefight, it is usually better to spread out colonists rather than have someone tank hits.

Fire management

As most furniture is flammable, you will need to extinguish any fires if you want to prevent damage. One option is to reinstall and trigger a firefoam popper inside, which also fireproofs the room, preventing any further fires.

If you prioritize the defeat of the raiders over the loss of your property, and the walls of the room are fireproof, you can simply let fires burn, or even start some more, while you evacuate the room and close the doors, cooking the raiders alive. Watch out for fire and heat spreading to nearby rooms.
Not effective against mechanoids as they aren't affected by temperature and cannot be set on fire.

Equipment

High-DPS or melee weapons work best to deal with drop pod attacks.
Mid-range weapons are also good for clearing out larger rooms.

Long-ranged weapons are less effective due to their low damage output and the confined nature of indoor spaces rendering their superior range unnecessary.

Explosive, incendiary or area denial weapons are excellent at room-clearing, but are not recommended except in dire situations due to heavy collateral damage.

Tribal raids

Tribal raiders arriving in large numbers.

Tribal raiders come with relatively poor equipment, instead relying on sheer numbers for power. Their neolithic weapons can dish out heavy damage despite their low technology level. They are also adept at combat, with many being acquainted to some combat skill or another.

Different strategies may be required, compared to pirate or outlander raids.

Tribal fighters

They can take more of a beating compared to other poorly armored enemies as some of the clothing items they wear gives them increased endurance against pain, but when compared with other decently armored enemies they are easier to kill individually as their clothing doesn't provide much protection overall.

Their archers or hunters can fire their bows from a somewhat long distance, sometimes forcing you out of cover to fire your shorter ranged weapons at them.
Warriors or berserkers don't use shields (unlike their pirate counterpart, the mercenary slasher), making them vulnerable to gunfire.

You should watch out for the pila wielded by heavy archers, as well as berserkers.

  • Despite the short range and slow fire rate, pila are incredibly deadly if they land, capable of killing or incapacitating unprotected colonists with a lucky shot to the heart, spine or limbs.
  • Berserkers carry excellent melee weapons that dish out incredible amounts of damage once they get close.

Weapons

You will need sufficient mid-long range firepower to take down tribal archers from a distance, for getting close to them in order to fire your guns is pretty much suicide. Long-ranged weapons beyond 32 tiles can effectively hit archers at maximum range, matching or outranging them.

Close-mid ranged weapons with high stopping power are good for taking down tribespeople that come too close to your defenders, but they alone cannot defeat tribals effectively just by staying in static cover.

Crowd control helps greatly in defeating tribal raids.

  • The Minigun is extremely effective as it can easily mow down the densely packed groups of tribal invaders.
  • All explosive weapons are devastating on tribals.
    • Rocket launchers deal heavy damage while being reasonably accurate.
    • High-explosive shells can pulverize a sizable group of tribals at once if they manage to hit.
    • Grenades are less effective as you have to risk a colonist or two in order to get in range.
  • Incendiary weapons are good at getting pesky archers out of cover for your colonists to hit.

Pacification

If you don't want tribes to send their warriors in the hundreds, you should capture, heal and release all incapacitated tribals (though if you see any good potential colonists you should keep them). Later on, when the relations warm a little, you can give them silver to pacify them, and even turn them to your side.


Mechanoids

Mechanoids come in 3 types, Scythers, Lancers (1.0) and Centipedes. They have much differing stats and weapons, meaning different tactics may be used. Both types are armored to some degree.

In many raids where they come/drop in at the edges, the Scythers will outrun the Centipedes by a great margin, giving some time to deal with them before the centipedes. However, they can and will support one another effectively, if given the chance for them to come together.

Unlike humanlike raiders, they do not flee, meaning that all of them have to be taken out to neutralize the threat. They do not actively use cover, either.

General strategy

Ranged mechanoids have a long attack range (at least 32 tiles), making them troublesome to deal with. To deal with this, lure them into closer range.

They are highly vulnerable to EMP damage, which can stun them, rending them hunks of helpless metal. This can open a window of opportunity where you safely engage at close range, or even with melee. Don't use them excessively as they can cause a mechanoid to adapt against them, making them less useful.

Scythers

Scythers are deadly with melee, and will charge head first at your defenders.

If fighting from a distance, high-damage weapons are essential to bursting them down before they reach your colonists.

As long as you have good armor and weapons, scythers can be relatively easily dispatched of, with melee ganking or even 1v1 fights.

They can be melee blocked with ease, with the added advantage of luring the other mechanoids closer to your base.

Lancers

Lancers are capable of long-range sniping attacks.

If fighting from a distance, cover is vital to getting the upper hand. Since scythers aren't particularly good shooters (equivalent to a level 10 shooter), you can outperform them at range with higher-skilled snipers.

They are vulnerable at close range, so if you wish melee rushing them can be used to take them down.

Centipedes

Centipedes, on the other hand, specialize in crowd control and area denial; the Minigun and Heavy charge blaster can annihilate groups of colonists, while the Inferno cannon sets your colonists ablaze and will burn down your base if you're not careful. They are incredibly durable, sporting thick armor and high health, and can take many hits before being downed.

Centipedes wielding the minigun and heavy charge blaster can be cheesed simply by spreading out your colonists with at least 3-tile gaps between each colonist. The centipede will be unable to hit at all due to the forced miss radii. Wide arc flanking is one method of achieving this.
The Inferno cannon, on the other hand, is significantly more annoying to deal with. Keep watch on your colonists at all times, and always send them back into cover after they get hit. Spreading colonists apart limits the number of colonists hit at once.

Despite their high resistance against sharp damage, shooting it is generally the best option. One good thing is that its large size makes it much easier to hit.

Engaging it in melee is possible but usually not recommended. While centipedes don't hit too hard in melee, if they are carrying the minigun or heavy charge blaster, they can eviscerate colonists at point-blank or deal massive damage to grouped up brawlers.
All nearby centipedes with the minigun or heavy charge blaster must either be engaged in melee or disabled to prevent this from happening.

Its slow speed and relatively poor blunt armor makes it an excellent target for high-explosive mortar attacks. Often you can pull off a couple of blows before it even reaches firing range, severely weakening it.

Crashed ships

Sometimes a crashed ship part will land on the map. They can have harmful effects such as reducing colonists' mood, killing any nearby plants or occasionally driving nearby animals mad. You cannot deconstruct the part, so you will need to shoot/ hit it until it is destroyed. When you damage the part, mechanoids will swarm out to 'defend' the ship.

As the mechanoids don't come out until triggered, you have some time to prepare. However, you don't have infinite time, either- poison ships can spread toxic material across the map, killing all plants in reach, causing serious losses to pastures or crops, and psychic ships are able to project powerful psychic waves, driving animals mad and sending colonists' mood plummeting.

Behavior

Mechanoids come out immediately when the part is damaged, or something is built right next to the ship part. They may also be triggered by the Firefoam popper explosion. Afterwards, they will guard the ship part, engaging any hostiles that come close. They will return to the part if targets stray too far away from the ship.
Once the ship part reaches 50% health, they will instead abandon the ship part and charge at your base directly.

Due to this behavior it is a better idea to engage them on the spot rather than luring them to base. Even if you manage to get them to charge, scythers can quickly catch up with your retreating colonists and attack.

Weapons

High-DPS weapons are optimal at destroying both the ship part and its defending mechanoids. Range does not matter that much as you can simply build cover close to the ship.

Due to the mechanoids spawning very close together after spawning, the minigun is extremely effective. It can quickly demolish both the ship part and the mechanoids with its unparalleled DPS, simply by aiming at the ship part.

Explosive weapons are useful, but keep in mind that the ship part will block the explosion. They do extra damage to the ship part.

As mechanoids tend to spawn very tightly packed, EMP mortar blasts are extremely effective against them, being able to stun a large number at once. As the ship part blocks EMP pulses, fire several mortars at once to hit all enemies with a single volley.

Incendiary weapons are a poor choice for any situation involving mechanoids or crashed ships, given that both are non-flammable and only take minimal incendiary explosion damage.

The orbital power beam targeter is the ultimate weapon against crashed ships. All you need to do is to aim the beam directly on the ship, and the beam will melt both the ship and its surrounding mechanoids.

Zoning animals

When dealing with a crashed psychic ship part that has been there for some time, do not let any of your tamed animals near it, for the ship part can drive them into manhunter mode. This is additionally harmful as they are capable of opening doors to attack your colonists.

Constructions

If you plan on shooting them, build sandbags or walls around the ship part as cover.

Building right next to the ship will instantly trigger the mechanoids. However, building them 1 tile away does not trigger them. This allows you to use IED traps to weaken a mechanoid swarm. Don't build too many or you will vaporize the mechanoid corpses, which can be deconstructed for resources at a Machining table.

Quick demolition

Rapidly destroying the ship part may be of interest to you, as the ship part both directly blocks shots and provides cover for the mechanoids. Destroying it allows your colonists to hit them more effectively, especially if you haven't completely surrounded the ship part.

Manhunters

Animals may randomly turn mad and become hostile due to various reasons.

When mad, they will actively attack humanlikes or mechanoids, and will not attack other structures unless provoked (such as seeing someone walk through a door). They are not sophisticated in their attacks and are only capable of actively using melee. Some can explode upon death for devastating results.

Animals

Any animal can be part of a manhunter pack. Each kind has its own statistics, and can be roughly grouped as follows:

  1. In terms of size:
    • Small: Small-sized animals. They tend to come in massive numbers and their small size makes them hard to hit.
    • Medium: Medium-sized animals. They do moderate damage, and some can run fairly fast.
    • Large: Large-sized animals that have high melee DPS up close but don't come in great numbers.
  2. In terms of speed:
    • Slow: Animals that run slower than an average colonist.
    • Fast: Animals that are faster than most colonists. Obviously the more dangerous of the two.
  3. Others:

Occurence

Mad animals can strike your colony in several ways.

  1. Singular mad animals may randomly attack.
  2. Manhunters packs can arrive in massive numbers, or have a few large and deadly animals. They come in a tight pack.
  3. Psychic waves drive all animals of a single species insane, directing them at your colonists. They are usually scattered at first, then proceed to converge on your colonists.
  4. In an unfortunate hunting incident, animals being hunted will turn on you, and may even bring their allies along.

Weapons

High DPS weapons are good at taking down packs at close to medium range.
Long-ranged weapons work to provide long-distance firepower when paired with other high damage weapons, but are inadequate on their own.

The sniper rifle works well against larger animals, but is poor against hard-to-hit small animals, as a missed shot is punishing due to its long reload, and its high damage is grossly overkill.

Longswords, or any other high-damage melee weapon, are a must-have to fight off animals at melee range, which often happens with fast animals.

Crowd control

The Minigun is an excellent weapon against manhunter packs of any size. At a distance, it can destroy the tightly packed groups of incoming animals, while at point-blank, it can rip large animals to shreds, often with just a single barrage of bullets. Aim for an animal in the middle of the pack, and the bullets will hit others around it as well.
Chain shotguns are also a good choice at defeating manhunter packs at close to point-blank range, though its short range makes it risky to use against faster enemies.

Explosives are excellent at clearing out manhunter packs, when used carefully. They can hit a lot of animals at once, and don't miss easily, especially against small animals which can evade bullets.

  • Rocket launchers are an effective yet easy-to-use one-use solution. Be careful when using them near your base or colonists though, and disengage if animals come dangerously close to allies.
  • Mortars aren't very useful as animals generally run faster than the mortars can hit, but if you have a kiting colonist or trained animals distracting them and you aim ahead, you can still achieve great results.
  • Grenades are good for groups, but are too short-ranged to be safe to use against raging animals.

Melee blocking

As with any full melee attacks, melee blocking is an extraordinarily efficient way to dispatch of manhunter packs. This is especially so if the animals are small such that they deal little damage before being killed, one after another.

Animals vs. Animals

One good way to fight off mad animals is with... more animals! Just draft anyone with Release-capable animals assigned, and set them out. Your colonists can watch safely from a distance, or take a potshot or two while watching the animals tear each other apart. Just remember to have someone mop up the bloodstains, haul the corpses of the fallen, as well as finish off any survivors.

Hit-and-run

A slower strategy is to draft a colonist, place it in a door to shoot a maddened animal, move the colonist back to safety and wait until the animal gives up and wanders off, then repeat. Be careful since this will draw the attention of surrounding maddened animals making them attack the door where the colonist came from, so be ready to repair it immediately.
You can either kill them directly or wait for blood loss to take its toll. Larger animals can be softened this way before you move in for the kill.

This method is best used if you don't have enough firepower to take on them directly, and you have durable enough doors to hold against animal attacks.

Kiting

Being unsophisticated in their tactics, they can be lured easily.

If you have good shooters that are fast (moving >140%), you can easily kite the faster animals.
The larger animals are usually slower and any colonist that has normal Moving will do fine against them, though it's still better with a faster-than-average colonist.
This is best combined with a long-range firing squad and turrets laying fire from a distance while they are chasing the colonist. Be sure that the animals do not lose track of your kiters otherwise they will switch targets and go for somebody else.

Frontlining

The traditional, less effective way is to engage the manhunters at the frontline. In this case, you will need some melee fighters to fight animals at close range and peel for your gunners.

While doing so, turrets can distract manhunters for your colonists, giving your colonists more time to shoot them while occupied by the turret. They may explode when destroyed, taking out a sizeable group of animals who won't run away from exploding turrets, switching to another target only after the turret is no more.

Waiting it out

If you have a perimeter wall or a superstructure base with decent food stocks, you can simply wait it out inside while they relentlessly swarm outside the walls. Some of them will exit manhunter mode once they fall asleep, and will act normally afterwards.

Remember not to let anyone outside unless your intent is to kill the animals.

They will actively attack doors if a colonist hides behind them; as a precaution, build it out of a sturdier material such as plasteel so they don't get destroyed during a manhunter attack. They will give up after a while if the doors are not destroyed. Alternatively, simply have a builder build a wall behind the door, totally preventing manhunters from entering even if they break the door.

Scavenging dead animals

Manhunter packs are a good source of meat for your colony, especially if you're low on food. If there are still maddened animals, wait until the other animals from the pack go to sleep, walk away far enough, or get a fast colonist to try and haul the dead ones away.

Infestations

Infestations will spawn under Overhead Mountains within 30 tiles of a colony structure. They can be a serious hazard in mountain bases due to the lack of free space to run away from with too many obstacles on the path, but not so much threat in open area (flat) maps. Insectoids are lightly armored, exclusively use melee and are slower than colonists. This gives them some protection against close range attacks, but leaves them vulnerable to ranged attacks and kiting tactics.

Infestation within mountain rooms bugs.png

If you don't destroy them fast enough, they can reproduce, giving rise to even more hives and insects. This is especially true if you happen to have forgotten about a hive, which given time can build itself into a giant mega-hive.

Behavior

Insects have a hive mindset; they will remain tending to their hive cluster, until they see an intruder, in which case they begin to engage all at once. They may also attack random furniture and structures in your colony.

Fighting infestations

The enclosed nature of mountain bases give colonists little distance to shoot from; thus, you may want some melee fighters to pair up with any ranged colonists.

Individual fighters will quickly get overwhelmed by the insects especially against large megaspiders, so you shouldn't trickle your defensive forces in; rather, send them all at once to overpower the insects.

Using fire

Fire is an effective way to clear early-mid stage infestations. If they spawn in an enclosed area with a door and plenty of flammables, all you need to do is to toss a molotov or shoot an incendiary launcher bolt into the room. The room will quickly catch fire, causing the temperature to rise fast, roasting the insects in it along with the hives.

You can provide extra fuel for the flame by building a lot of cheap wooden furniture, such as stools, then deconstructing them and forbidding the wood. This is more resource efficient than having colonists haul entire stacks of wood to burn.

If there aren't flammables, you can still keep shooting the hives. They can catch fire, along with the fuel puddles created on the ground.

As any items inside the room are likely to catch fire and be destroyed, this tactic is not recommended in a place with many valuables such as warehouses. Also be careful with the heat spreading to nearby rooms. Insects trapped in uncomfortable temperatures will quickly attempt to dig out to escape. If they don't fall unconscious fast enough they may survive to break out and attack.

Explosives

Explosives are useful against large infestations. The Triple rocket launcher can raze infestations instantly. A single use Doomsday rocket launcher will deal massive damage over a large area. Frag grenades are unlimited and work well if you have the courage to send someone to close range. One blast can get several insects.
Explosive animals (boomalopes or boomrats) are also effective at clearing out infestations. Have them march straight into the hive by zoning them there. When the insects attack, the animals will be injured and explode, setting the insects and hives on fire.

Mortars are useless against the hives themselves as they can't hit anything below an overhead mountain. However they are an option when fighting the insects in open space, with the explosions capable of severely injuring the insects, taking out the smaller ones in 1-2 hits.

Late-stage infestations

If you've accidentally left a hive or two behind or totally ignored an infestation, after a few seasons you will have a giant hive community sprawling. This is extremely hard to treat, especially if you're low on colonists.

If you're still on early-midgame, it's generally recommended that you pack up and run. If not, however, you will have to deal with them slowly. You need to lure the insects out, then defeat them to buy time for others to enter and destroy the hives. Kiting is a possibility due to their slower speeds, provided they continue to chase down your colonists.

Explosives are recommended as they deal immense damage to the closely packed hives and insects. This is especially so with the doomsday rocket launcher, which can set entire infestations on fire, destroying the hives and severely weakening the insects.

Melee blocking

Usage of this tactic allows you to defeat insects efficiently and maybe even stand a chance against massive infestations if for some reason fire isn't viable, but don't get cocky.

Chokepoints can arise on their own from insects digging out; simply wait for them to tunnel through and massacre them once they exit.

Prevention

If you only have a few tiles of Overhead Mountain then it's best that you fill it up with walls to prevent any infestations from happening. If you are in a mountain base, then you will need to do more than that.

Baiting

You can mine out rooms a distance away from your colony to somehow control insects to nest there, instead of letting them spawn right in the middle of your base. Place some cheap flammable furniture inside to confuse the insects into thinking it's a prospective nesting spot, as well as to light on fire for a quick solution to an infestation problem.

A well-lit base discourages insects from nesting, though it can still happen. If you bait insects to spawn elsewhere the chance of an infestation spawning inside is greatly reduced.

If you want the insect trap to automatically kill insects, put an IED incendiary trap inside the room, next to the flammables. Once an infestation spawns the insects will trigger the trap, lighting the room on fire and broiling the insects.

Alternatively, fill it with a few deadfall traps to weaken them before they strike your base, giving you the advantage. It also preserves the hives, which can be either good or bad.

Deep freezing

An interesting way to completely prevent infestations is to simply set your base temperature below -17°C with coolers, and have everyone in the colony wear parkas.

This means that the 'Slept in the cold' debuff will be prevalent in the colony, however, so you will need something to offset the mood.

Deep drill infestations

Deep drills can unearth insect hives, which will result in enraged insects charging up to attack after a while.

Prison breaks

If you have prisoners (or potential colonists or hats) on hand, always expect them to break out any time. This is more so if you have many of them, each one ready to incite a riot whenever the guards aren't looking.

Escaping prisoners can open any colony door, and will snatch weapons whenever they see one.

Strategy

You should block the prisoners with armored wardens carrying blunt weapons, or melee attacks with guns. They will fight and down the prisoners while blocking their exit, buying time for reinforcements.

Against already injured yet unarmed prisoners, send 1 brawler per prisoner to minimize the risk of beating them to death.
For those at full health, 2 unarmed wardens or 1 skilled one can tackle a full-health unarmed prisoner without the wardens being downed in most cases.

Ranged wardens should attack when the prisoners are blocked by melee wardens so they can attack from a distance without much danger, and their weapons won't land in the enemy hands so easily. Don't fire too much at them as you risk permanent damage as well as accidentally killing the prisoner.

Weapons

You goal here isn't to kill the prisoners, it's to down them so you can recapture them.

  • Blunt melee weapons such as the mace is a good choice for wardens to down escapees. The wounds don't bleed, nor will they be infected, giving them higher survival chances overall.
  • At a distance, use moderate DPS weapons that won't deal too much damage to the prisoners, or to your people when the prisoners pick them up.
  • Don't use high damage per hit weapons such as sniper rifles or longswords, as you risk instantly killing them or destroying an important part.

Turrets

Turrets can be used as a form of distraction and supplementary firepower against prison breaks. Station them outside the prison doors, and they will fire on the escapees. They deliver good stopping power at short ranges, and leave no viable weapons that can be picked up. Prisoners also tend to stop to fight the turrets, giving wardens time to reach them.

1-2 is enough for most prisons. Don't put too many otherwise the turrets may kill the prisoners before you can intervene.

Ambushes

Defensive battles don't always happen at base. Sometimes it may happen far away from it, striking one of your caravans, perhaps loaded with plenty of silver. Or maybe they creep to your traders and demand ransom, which you don't feel like paying. You always need to be prepared for ambushes when you send out caravans.

Escort

Sending just one or two colonists in any caravan is usually not advised except in very short-distance and light trips as they will not be able to fend off an ambush. In this case, have combat-capable escort members which can fight and carry items, as well as medics who will patch up your colonists after battles.

If you have lots of attack animals, you can also send just 1 colonist skilled in handling, and a lot of attack animals. They can swarm any incoming attackers, and you can leave colonists back at base for work. Remember to take into account the animals' food needs; grazing animals work best for this reason.

On the other hand, if you are not carrying much besides a lone colonist, leaving him to go alone is helpful as lone colonists are hard to detect, reducing the likelihood of ambushes.

Ambush site

The ambush site is small, restricting the space where you can conduct your battle. This renders many tactics obsolete, such as long-ranged sniping or kiting. You will often have to face off the enemy in a direct gunfight or brawl.

Besides this, you can't escape the fight until it's over, leaving no choice but to fight back.

Cover and positioning

Excellent defensive position against ambushes. Colonists behind walls will enjoy up to 75% full cover, while pirates will only receive 25% at most. Two brawlers are ready to execute a melee sortie, while another is ready to peel for the gunners. Combined with good equipment, this allows the fight to be won with few injuries even when outnumbered.

You should be hiding behind walls for cover if possible, as they provide up to 75% cover, but if they are not available, hide behind rock chunks or trees. Space out your defenders to reduce the amount of collateral damage the pirates deal.

If you have time, go somewhere where there is cover for you, but not the enemy. This gives you a significant upper hand in defensive battles.

Melee sorties or rushes work well if you have brawlers for they can traverse the short distances.

Items

You will need to bring some items so you can be prepared for a surprise attack.

Weapons

You usually don't have weapons to switch in a caravan unless you're bringing more than you need with you, so choosing the right weapons for your escort party is important.

  • High-DPS weapons are optimal for dealing with ambushes.
  • Long-ranged weapons are good for taking down targets at medium-long range, however their low DPS may offset their range advantage in an ambush.
  • Miniguns are good against tightly-packed raiders hiding behind cover in an ambush. However, their heavy weight and movement speed reduction means you may want to reconsider bringing one.
  • Melee weapons can help fight off enemy brawlers, or disrupt enemies behind cover. You should have at least 1 melee fighter in each escort.

Medicine

You should have some medicine handy so your colonists can patch themselves up after the battle.

Medicine should be your choice here; you should try to get good treatment to reduce chance of infection, as colonists don't get much rest in a caravan. Herbal medicine is useful if you have a good doctor on hand.

Aftermath

You can reform the caravan immediately after the battle is ended; you can bring along any downed colonists, as well as capture downed enemies. The caravan members will tend to themselves shortly afterwards.

Alternatively, you can stay and forage from the ambush map before you leave.