note that in rpg you don't stimulate the physics. every tick of combat you send an effect packet that describe that turn action result and the client side plays

note that in rpg you don't stimulate the physics. every tick of combat you send an effect packet that describe that turn action result and the client side plays whatever effect is needed once a combat session is initiated you don't need that much prediction going on because where you move is uncorrelated to where a fireball hit or not, only player stats. the real exception are are effect, as the client need to reconcile them, but the client can chat as much as it wants as long as the presentation matches the server player stats: it can for example position area effect that hit on the server in a position such as the player hit was in range. the client only had to make sure action result are in sync, not the world physical station whole