Injury

Humanoids, animals, and mechanoids sustain injuries from sources including melee weapons, weapons fire, explosions, ceiling collapses, and fire. Each source of damage comes with a specific Damage Type. Colonists, visitors, and prisoners can be operated upon and may suffer an injury from a surgical mistake. Each kind of injury has a value of pain, a description for its scar, and flavor text for being mended by medicine. A colonist in shock from extreme pain or incapacitated due to loss of movement becomes ' downed'. Doctors will automatically rescue downed colonists.

Injury types

Main article: Health Difficulties

Different weapons cause different types of injuries. For example, a mace will crush, a longsword will cut, and fire will burn. The type of injury impacts the amount of pain it causes, the rate of bleeding, and the chance it gets infected.

Pain

Main article: Pain

Injuries cause pain to a colonist, and excessive pain can cause a pawn to be downed from pain shock.

Most pawns go into pain shock once their pain exceeds 80% except for wimps who are downed at 20% pain.

Recovering from injuries

Injured colonists will recover from their wounds over time. Every couple of minutes in game, a random injury will be healed by a small amount. This healing reduces the severity of the injury, and when the severity of the injury reaches zero the injury is fully healed.

Every 600 ticks heal rate × 0.01 points of damage are healed from a randomly selected (non-permanent) wound. The exact heal rate is determined by adding up three factors:

Default healing rate: All pawns have a base heal rate of 8
Is the pawn lying down or in a bed?: +4 for resting on a sleeping spot or the ground, +8 for resting on a bed / bedroll, and +14 for resting on a hospital bed
Is the wound tended?: +4 for a 0% quality tend and +0.08 per point of tend quality, up to +12 at 100% tend quality

To put this in perspective, consider a colonist who has taken 20hp of damage to various body parts. The colonist heals heal rate × 0.01 points of damage every 600 ticks, so they'll need 20 ÷ (heal rate × 0.01) ticks to fully recover. To give a few examples:

Do nothing: With no tending or rest, they get the base heal rate of 8, so it'll take 150,000 ticks (2 and a half in-game days) to heal
Basic tend and resting: With a 40% tend quality (+7.2) and rest in a non-hospital bed (+8), they have a heal rate of 8 + 7.2 + 8 = 23.2, so it'll take 51,724 ticks to heal (around 21 hours in game)
Best quality care: With 100% tend quality (+12) and rest in a hospital bed (+14), they have a heal rate of 8 + 12 + 14 = 34, so it'll take 35,294 ticks to heal (around 14 hours in game)

Note that immunity gain speed has no influence on the recovery rate from injuries -- it only affects recovery from disease

Scarring

Scars are permanent markers of injuries. They permanently lower the maximum health of the scarred body part, making it easier to damage the affected body part in the future. They also cause a character a small amount of pain, even if the relevant body part is fully healed. Pain from scars results in a permanent mood penalty for non-masochistic characters. For a colonist with the Masochist trait, scar pain will provide a continual mood bonus instead of penalty.

Sometimes colonists are generated with minor scars and old gunshots already in place. Some body parts also scar instantly upon injury.

It is possible to remove the pain from some scars by surgically implanting artificial replacements. Artificial body parts will never scar.

Scars can be treated by luciferium, however the cost of using it usually outweighs the benefit, unless used on numerous scars, or a permanent brain injury.

Another way to work around scar pain is to implement a Painstopper, preventing all ongoing pain. The downside to this, however, is that should the pawn with an installed Painstopper take serious damage - they won't go down until they either lose a leg (or have it heavily injured), or die. Therefore, you should be extra watchful of their health as to decide whether to withdraw them from a controllable scenario (i.e. combat), as to prevent them from losing their life.

Trauma Savant

Being shot in the brain can cause the trauma savant condition.

A pawn may become a trauma savant upon taking and surviving an injury to the Brain. Certain capabilities will rise and some will fall.

Trauma Savant currently removes all ability to socialise and opinions of others, capability of Talking and Hearing (both capped at 0%), but increases Manipulation by 50%, and restores full brain functioning (meaning consciousness and other functions will be normal) - this is great for doctors and general workers, but it'll make affected wardens or traders a write-off in that aspect.

There is a 12% chance of any pawn becoming a trauma savant upon receiving brain damage. It does not have to be a humanlike, and can sometimes be seen applied on animals.

While Trauma Savant can be cured it is difficult and expensive, it is usually better to take advantage of the increased manipulation. To cure Trama Savant you will need a Healer mech serum, however this will heal the brain scarring first so you have to either use multiple Healer mech serum or first apply Luciferium which will eventually heal all the scarring at which point you can apply the Healer mech serum when Trauma Savant is the only health negative left.

Trivia

Brain injuries in Rimworld cause large amounts of pain (20% or higher for a 5 hp wound), often rendering a pawn permanently comatose in extreme cases, this being due to pain stacking with the reduced part efficiency. However, in real life the human brain has no pain receptors. This is due to how if anything manages to get into the brain and damage it, it will already have caused intense pain from having to penetrate the skull, and the person is likely going to be fatally wounded regardless of how they react. Headaches are often caused by receptors triggering elsewhere in the head or neck, not by receptors in the brain