My group did testing on this today. grass,bushes, tree structure walls and buildings can all be modified or removed. grass,bushes and trees were stable. Buildings and structures cause crashes after time.
removing those files allowed a player/client to see objects obscured and not be effected by the collision detection.
Game start states files are missing but allows the player to play anyways.
TLDR. by removing certain files a player can shoot/see through walls/trees/building/grass/bushes