CombatExtended and the combat overhaul it brings to RimWorld

A total conversion of the combat system, not a balance tweak

Combat Extended completely overhauls combat. It adds new shooting and melee mechanics, an inventory system, and rebalances the health system.

The scale of that is worth being clear about, because RimWorld has a long history of combat mods and most of them adjust numbers. This one replaces the underlying model. The vanilla percentage based shooting system is completely gone, replaced by a ballistic model where bullets fly along a trajectory and intersect hitboxes. Vanilla percentage based armour is gone too, replaced by a deflection-based model in which projectiles carry armour penetration values that determine whether a bullet penetrates and how much damage it loses.

The consequence is stated bluntly in the documentation: the mod requires a new save to play, and should not be removed from existing saves. That is not a warning about edge cases. It is a warning that the mod rewrites the rules the rest of the game reads, so a save created with it in place is a save built around different assumptions.

The audience is therefore a player starting fresh, or a player willing to restart, who wants combat decided by simulation. The project is C# with a Development default branch, the last push was on 2026-10-16, and the recent releases are v1.6.7.4.0 from 2026-10-15, its release candidate v1.6.7.4.0-rc1 from 2026-10-10, and v1.6.7.3.0-hotfix.1 from 2026-06-28. The repository is not archived, and there is a Discord community and a Steam Workshop entry alongside the GitHub releases.

The scale of the repository also signals the ambition. The top-level entries include Defs/, Patches/, ModPatches/, Source/, Assemblies/, About/, Ideology/, Biotech/, Anomaly/, Odyssey/ and Royalty/, which are the definitions for each of RimWorld's recent content expansions, along with Sounds/, Textures/ and Languages/. A mod that patches itself into every expansion has to be maintained against every expansion.

The ballistic model, and why a helmet matters

The shooting system is the part of the mod that changes how a fight feels, and the documentation is specific about the consequences.

Range and damage have been completely rebalanced, with the direct consequence that no more raiders shrugging off dozens of bullets or sniping with pistols. Guns dominate in their assigned role and range bracket. Rifles excel at medium-long range engagements, machine guns are good at area suppression, and shotguns and submachine guns are lethal in close quarters.

That last structure is the design. A weapon is not a damage number with a spread chance attached, it is a tool for a distance, and the ranges are what make the choices interesting.

The most illustrative detail is that bullets track their height as part of their trajectory. When a bullet strikes a pawn, that affects where it hits, so someone crouching behind sandbags can only be shot in the head, which is why you should make sure they wear a protective helmet. That single sentence contains the whole model. Cover works, but it changes which part of the body is exposed rather than providing a damage reduction, and a head is a small target for a projectile to find.

On top of the ballistics there are new mechanics. Weapons can switch between different aim and fire modes. Pawns in the open crouch in combat when not moving, which makes them harder to hit. Projectiles create suppression on near misses, and as suppression builds, pawns run for cover even against orders and suffer from significantly decreased accuracy; if suppression reaches a critical threshold, pawns hunker down in panic and become completely unresponsive.

That suppression behaviour is a small simulation of morale, and the detail that pawns will break orders to take cover is what makes it read as a combat system rather than a stat block. Ranged weapons also require ammo and can switch between ammo types such as armour-piercing and high-explosive rounds.

Melee with crits, parries and ripostes

The melee system is rebuilt around three new statistics: critical hit chance and parry chance, alongside the existing melee skill.

Critical hits produce different effects depending on the source of the attack. Blunt weapons stun the opponent, sharp weapons have twice as much armour penetration, and animals cause knockdown. The differentiation is what gives weapon choice a purpose beyond the damage number.

Parrying is the more interesting mechanic. On a successful parry the defender's weapon or shield absorbs the attack, unarmed parries do half damage, and a pawn can only parry a limited number of times depending on melee skill and attack speed. A parry can then roll for a critical hit, in which case the defender gets a free non-critical hit against the attacker, which the documentation calls a riposte.

In combat, critical hit and parry chance are compared against the opponent's to determine the final hit chances. The documentation adds a warning that you should not expect a level 1 fighter to parry a level 20, which is a fair statement of what a skill comparison does and a useful one, because it tells you that the system's interest is in relative skill rather than in any absolute chance.

Different melee weapons give bonuses to crit, parry and dodge, and dodge has been rebalanced on its own.

The result is a melee system with a defensive and an offensive line. A pawn with a high parry chance and a shield can blunt an engagement without landing a hit, and the riposte rule means a successful parry converts into offence rather than being a pure block. That is a different shape of fight from the vanilla one, where melee is a skill check that resolves in one number.

Deflection armour and the shield trade-off

The armour system is the second replacement rather than rebalance, and it changes what equipment means.

The vanilla percentage based armour system is gone. Combat Extended replaces it with a deflection-based model where projectiles have armour penetration, which determines whether a bullet penetrates and how much damage it loses. The worked example given is that a rifle bullet will go straight through a synthread parka but will completely bounce off of legendary power armour.

Note what the model does not say. It is not a percentage subtracted from damage, it is a question of whether the projectile gets through at all. That means armour is a discrete outcome rather than a graded reduction, and a rifle against a parka produces a very different result from a rifle against powered armour. Equipment choice becomes a statement about what you expect to be shot at with.

Shields are the other half. New shields provide additional protection against ranged fire. Basic melee shields can be made at the smithy and block arrows, and researching machining gives access to modern ballistic shields with improved coverage and protection against gunfire.

The interesting part is what shields cost. Equipping a shield confers penalties to melee hit chance and shooting accuracy, and it prevents using two-handed weapons such as rifles, longswords and spears. In melee, shields increase parry chances.

So a shield is a real decision with a real cost rather than a strict upgrade. It converts your weapon options and taxes both your shooting and your melee accuracy, and what it buys is survivability against ranged fire. In a game where the documentation says a crouched pawn behind sandbags can only be shot in the head, protection against ranged fire is worth something, and the restriction on two-handed weapons is the mechanism that stops it from dominating.

The parry interaction is the detail that ties the two systems together. A shield is not only a ranged defence, it is a melee tool, and the mod makes the trade explicit rather than hiding it.

Inventory, loadouts and what colonists carry

The inventory system is the feature with the widest reach into the rest of the game, because it changes how a colony is run rather than how a fight is resolved.

Pawns can pick up various items and carry them in their inventory for easy access. Carrying capacity is limited by weight and bulk. High weight negatively affects movement speed, and bulk can be increased by equipping tactical vests and backpacks but will negatively affect workspeed.

Two separate axes with two separate penalties is the meaningful part. A colonist hauling a stack of medicine is slowed down, and a colonist wearing a heavy armour vest works more slowly at the workbench. Since RimWorld is a colony sim where work speed compounds over a whole day, the bulk penalty is the one that changes your production numbers, and the weight penalty is the one that changes your map layout, because slow pawns respond badly during a raid.

Apparel mostly does not add to bulk when worn, but some items are very heavy and/or bulky, such as armour vests. If an apparel has a Worn bulk stat, it will increase bulk by that much when worn.

Loadouts are the automation layer on top. By default colonists will only pick up ammo for their equipped weapon. A loadout is a list of things a colonist should automatically keep in their inventory, such as meals, ammo and sidearms. Colonists with a loadout will automatically clear their inventory of surplus items and pick up anything they are missing.

The documented use is to automate picking up ammo, grenades and other consumables, which is exactly the chore that makes a late-game colony feel like administration rather than play. The loadout also carries a risk the documentation does not spell out: a colonist clearing surplus items to make room for a loadout will do so automatically, so a loadout that includes only one of two consumable types leaves the other on the floor.

Medical changes, and building the mod yourself

The health system rebalance is the part with the sharpest edges, and it changes what a firefight does to a colony.

RNG death on downed has been disabled, so there are no more wimp visitors dying from one squirrel bite. Body part coverage has been overhauled, and torso shots are significantly more likely to hit a vital organ. Limbs are overall tougher. Bleed rates of internal organs are significantly higher, so someone shot in the heart or lung will only have a few hours before they bleed out and require immediate medical attention, and internal organs continue bleeding when destroyed.

Stabilising is the counterweight. Pawns can use medicine to stabilise bleeding, and it requires one medicine per stabilised pawn. Stabilise temporarily reduces the bleed rate of all wounds on a pawn and wear,

Taken together, the medical changes invert the usual priority. In vanilla RimWorld a downed colonist is a resource problem. Here, an internal organ hit is a clock, and the medicine you spend stabilising one patient is the medicine you do not have for the next one, which is why the balance of shots landing on torsos matters more than the raw damage numbers.

For players who want the bleeding edge, the development section explains that the repository contains an uncompiled assembly file that will not work with the latest changes, and that the development snapshot zip is updated a few minutes after a pull request is merged to the Development branch. Pull requests also have their own built versions, provided by the GitHub Actions bot.

Building from source is a make-driven process. The Makefile defines the assembly targets and the compatibility assemblies, and it clones a publiciser tool as a prerequisite:

all: Assemblies/CombatExtended.dll CompatAssemblies AssembliesCompat $(PUBLICIZER)
.PHONY: all CompatAssemblies

The make targets are all, AssembliesCompat, and the individual assembly rules, which invoke a Python driver to compile the C# projects and pass the reference and publiciser paths. The Building.md file in the repository holds the full instructions.

The supported third-party mod list lives in SupportedThirdPartyMods.md, and a mod this invasive will conflict with anything that also touches combat.

Editorial conclusion

Combat Extended is a good fit for a RimWorld player who has found the vanilla hit system unsatisfying and wants shooting, armour and melee decided by simulation rather than a percentage, because the rebalance is deep enough that combat plays differently at every range bracket. It is a poor fit for an existing save, since the mod requires a new save and should not be removed from existing ones, and a poor fit if you build around a mod stack that expects the vanilla combat model. Before installing, check the SupportedThirdPartyMods.md file for the mod combinations you already run, and take the development snapshot rather than the repository itself, because the repository holds an uncompiled assembly that will not work with the latest changes.

Frequently asked questions

Official sources

1. CombatExtended-Continued/CombatExtended on GitHub
2. Issues
3. README
4. Releases