Unreal/Houdini VAT
Unreal has a very cool feature in its materials called World Position Offset. Coming from VFX I'm totally unfamiliar with it (the closest thing might be vector displacement?). You can move your geometry based on the color of a texture. It's very fast to process, that's how you can get all those moving trees and grass in Unreal.
Houdini has a tool where you can export animations with the World Position Offset (Houdini calls them Vertex Animated Textures). I started with a vellum sim of the falling pigheads and then tried with 1000 RBD objects. I tried a version with 3000 but I could see a lot of the skulls popping and disappearing.
The last thing I tried was their new tool for exporting flipbooks. Unreal can't import volumes yet (as far as I know) so you have to pre-render them. Houdini has a lot of really nice features, exporting not just the color but normals and motion vectors to allow for some simple relighting (which I didn't try here) and smooth retiming.
