An animation sharing system between generic humanoid rigs. There is another free-to-use game engine that has had one since 2013… I’ve bought thousands of FBX animations and importing and adjusting them all to work with Unreal just hardly ever even works out right.
It’s frustrating when all I have to do with the other engine is import my model and tell the engine that it is a humanoid rig, and to enforce a t-pose and then it sorts pretty much everything out for me automatically, doesn’t even take a full minute.