Mod «Big and Small Genes» for Rimworld (v1.4)

This core mod includes a number of Biotech genes, traits, and the C# framework to make things in other mods work.

In total the mod contains 68 genes (as of writing), 11 of which are related to size. All are balanced for vanilla. If you feel anything is "OP", please send your feedback and I'll look into it.

This was originally part of the Big and Small Races, but was split into its own mod so that you don't have to deal with Jotun if you just wanted small goblins, big space marines, or whatever suits your fancy,

If you want the mod I made which makes use of the genes included here see the Big and Small Races mod.

Mod requires:
DLC Biotech
Big and Small + Prerequisites Framework

If you are using [VL] Facial Animations with HAR you may need to turn off the 'Experimental Beard Misalignment Fix' if you get misaligned beards.

If you are getting cropped pawns turn off Texture Caching in Vanilla Expanded Framework. This especially happens if you are using Camera+ which confuses Rimworld's Caching system.

This is just a sample of genes from the mod. As of writing the mod has 150+ genes. Many of the genes do not spawn in genepacks and are found only on specific xenohumans. This is often the case with purely cosmetic genes in order to avoid bloating genepacks.



Beyond game-play affecting genes like the above there is also a number of cosmetic genes such as horns, a skin & hair colours, etc. Most of these are either rare or simply will not spawn in genepacks to avoid bloating your chances of finding things you actually want.

The offset genes will increase or decrease the size of a pawn by a certain value. For obvious reasons there is a limit to how small a pawn can get. This could be considered the primary way in which a pawn's size is changed.

These genes will multiply the pawn by a certain value. This stacks with the Offset genes, and means that you can have a Jotun-frame pawn with dwarfism, or a Dwarf-frame pawn with gigantism. This will also work as you'd expect with pawns which have a base size smaller or larger than the 1.0 of humans.

There are traits working identically with the Size Multiplier Genes mentioned above. If a size-multiplier gene is present on a pawn with such a trait it will override the trait.

• Dramatic effect on max nutrition.
• Very large effect on nutrition use.
• Alters Body Size attribute and associated traits
• Dramatically modifies health.
• Alters damage, a bit less than the linear increase.
• Large effect on Melee Dodge chance benefitting small characters.
• Very large effect on Self-"Production" from Alpha Genes and Biotech Expansion genes.

Animals can now also be shrunken down or enlarged.

Shrunken animals retain a decent amount of their previous sturdiness, become faster and more evasive, but are less capable of dishing out pain. They also eat less.

Enlarged animals are bigger, sturdier, better and dishing out pain, but and slower and hungrier. Giantizing small animals has the most dramatic effect.

All 5 gene tools are craftable at the Drug Lab.

Adds a few giant weapons that can only be wielded by Giant pawns, Herculean pawn (Roo's Minotaurs), or Warcaskets.


Giant hammer, giant club,, giant warhammer, jotun longsword, Skrýmir's Mallet, Sword of Surtr,


Throwing boulders, jotun javelin, warmech anti-material rifle, and warmech minigun and rocket launcher.

When using this mod your pawns will also grab multiple meals if it would be required to fill their hunger bar.


The mod added Large variants of most vanilla meals to make feeding large pawns easier before they could grab multiple meals. They are a bit redundant now that pawns can grab several meals but it is left in as legacy to avoid breaking people's saves.

Vanilla Weapons Expanded - Heavy Weapons
Giant pawns (Jotun/Ogre frame and up) can use Heavy weapons without Tough or Exoskeletons.

Roo's Minotaur Xenotype
Giant pawns can use the big minotaur weapons, they are also patched to behave as if "Herculean" for the purpose of the mod's, uh, "crushed pelvis" mechanic. Ow.

Vanilla Factions Expanded: Pirates
Giant pawns can use Warcasket weapons.

Vanilla Races Expanded - Android
Adds a number of genes to your Android crafting menu, including the most notable size-genes.

MH: Android Tiers Core
Adds several frames so you can make big and small androids or biometric units.

Universum/RimNauts & Save our Ship 2
Adds genes which lets pawns handle the vacuum of space.

Zombieland
Depending on genes some pawns will not be infected or rise as zombies. Ghouls & Returned have a gene which makes zombies ignore them.

None known.

Contrary to claims, Outland Genetics is not incompatible with this mod. You can safely use them together. Let me know if this changes. (2023-04-08)

You are free to make use of anything in this mod for your own mods.

.Phaneron
Made the gorgeous art for the giant-sized minigun, tribal hammer, and the ultra-tech sword and hammer!

Hyou
Creator of the awesome giant rocket launcher!

19.10.23 (1.4)

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13.10.23 (1.4)

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09.10.23 (1.4)

• Fixed a missing icon

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06.10.23 (1.4)

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02.10.23 (1.4)

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