This was a test of having lots of animated meshes simulated with Niagara, like a crowd. The mesh uses Vertex Animation like this:
Then there is some basic brute force collision/velocity alignment.
The mesh is quite unoptimized, and there could be some manual Lod:ing and using Neighbour Grid for collision to get more out of it. Would be fun to see how far it could be pushed.
This one is good a inspiration: