yeah physx is limited in 3dgs, so I used OBB. it was also buggy, but with some c-traces done before movement, I had a good enough result, what you can find it in MapBuilder (used for testing the map with that soldier character). it is not a complex one, e.g. no doors, no climbing, but works, and imo can be easily extended, in my RTS I used something similar for the unit-unit push-bounce collision handling.