I have been playing with the new Unity Physics package (currently version 0.1.0). It seems the Unity Physics solution is not frame-rate independent. I found this by comparing two falling cubes, one using PhysX and one using Unity Physics. Upon a laggy scene startup, the Unity Physics cube does not fall constantly in regards to time, and therefore lands later than the PhysX cube. (Blue cube: PhysX, Red Cube: Unity Physics) Is the frame-rate independentness (ehh, english) simply the consequence of using deterministic physics simulations? Or, would it be possible to force the simulation to run every fixed tilmestep using the current API? It'd be cool to know if the people working on Unity Physics are already planning on some easy way to make the simulation rate constant.