Mod should supply an 'anim' directory structured like our 'game/Assets/anim' directory.
The game will look for a *_anim.bytes, *_build.bytes, and *.pngs for textures. The folder name dictates the animation name. If an existing animation is modded, the one in game is replaced; otherwise a new animation is added.
ONI v364722 changelog which about mods: