Auto mortar

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Auto mortar

Auto mortar

A self-powered, self-loading, automatic mortar. It can hit targets at any distance, over walls, but is quite inaccurate.

Base Stats

BuildingMechanoid cluster
Path Cost


2 × 2
pass through only
Cover Effectiveness

Ranged Combat

50 dmg (Bomb)
Armor penetration
ticks (0.07 secs)
500 tile(s)
Minimum Range
29.9 tiles
41 (m/s)
Burst Count
1 (per burst)
Miss Radius
10 tile(s)
Stopping power
Destroy yield
Steel slag chunk 1 + Steel 60 + Plasteel 10 + Reinforced barrel 1

An auto mortar is a hostile building that appears in mech clusters and autonomously launches explosives similar to a manned mortar.


Auto mortars only spawn in mech clusters. Like the condition causers, it counts as a cluster's problem causer, of which each can cluster can only have one. It generates four times more often than the other problem causers, but only costs the cluster 220 combat points rather than 750, so the cluster will have more other threats.

They cannot be claimed by the player, and must be destroyed for the cluster to be considered defeated.


The auto mortar fires shells equivalent to high explosive shells, which explode as normal to deal 50 Bomb damage in a 2.9-tile radius but do not require restocking or reloading. Like normal mortars, it has a forced miss radius of 10 tiles, and if you roof over it, it can't fire. Note that unlike normal mortars, its forced miss radius does not increase to 13 if the Classic mortars storyteller option is enabled. Valid targets appear to be colonists, buildings and, unlike siege mortars, player owned animals.

If it is damaged beyond 20% HP (52 HP) it may explode but it is not a certainty. The mortar will spark and emit a hissing sound shortly before exploding 240 ticks (4 secs) later. The explosion deals 50 Bomb damage in a 4.9 tile radius centered around the mortar's bottom left cell.

They are a source of the reinforced barrels needed to construct mortars. Reinforced barrels will not spawn if the Classic mortars storyteller option is enabled.

Like all mech cluster buildings, they not only have a Flammability of 0%, but also take no damage from attacks with the Flame damage type. This is in contrast to, for example, a stone wall which will not be ignited by molotov cocktails but will take the 10 flame damage from the initial attack.

Auto mortars must be destroyed for the mech cluster to be defeated.


Auto mortars are like a siege which lasts until the building is completely destroyed. Even a few rounds can blow up your supplies, production facilities, and walls, making it an extremely high priority threat. Like other condition causers, it can start immediately active or remain dormant for a few days. Waking up a mech cluster will not cause the auto mortar to immediately start firing.

If the mech cluster doesn't have a proximity activator, then you may be able to roof over the auto mortar. You can use the cluster's own walls, or place a wall or column 6 tiles away from any mech or mech building - this is far enough to not trigger the cluster. The action of placing roof will not aggravate the mechs, either. Unless the wall is destroyed, you'll be safe from the auto mortar.

Version history[edit]

  • ? - Added.[Release?]
  • 1.2.2753 - Fix: Auto mortars are always active.