The latest dev post is one of those things that points out how deep the simulation of the game goes.
One of the new improvements is tissue tracking and creatures made of materials like flesh and bone. Once implemented it led to an interesting problem: undead skeletons.
The issue here is that when a skeleton is created, it strips away all of their rottable tissues, but that leaves the head completely empty (things like the skull are sub-parts), and this means the skull is essentially floating separate from the spine (which is also floating). Handling it correctly is a bit of project, so I just stuck the slightest bit of totally rotten muscle on them for now to hang things together. The only downside here is that you'll occasionally see muscles in the combat text for skeletons. It all raises the question of exactly how the bones are moving and supporting their weight in the first place, which I suppose will start to be answered when I get to the curse entry on dev_next. For now, they are held together by wisps of very strong rotten muscle that inexplicably work. In terms of mods, for each part that is completely rottable, it selects the deepest non-subordinate tissue marked as a connector and keeps it. For a dwarf, legs and arms just use bone, while the head and body have to cheat. It should work for rotting away any undead creature to a "skeleton". I haven't tested them, but "skeletal" insects should end up being hollow exoskeletal husks with this method.
So basically the game was saying undead skeletons couldn't exist because without any muscle or tendons the head would just fall off (and I'm guessing that would "kill" it).
Games have interesting unintended "bugs" like Quakes bunny hopping causing you to move faster than normal, or skiing in Tribes. But how many games come back with a "This creature cannot exists because it violates the rules of biology and physics"?
