Chipmunk repeatability

[slembcke]

So if you have two iPhones both running an ARMv7 binary and both with the exact same starting conditions, then yes you should be able to get the same simulation. If you run it on one of the newer devices with a newer CPU and run the ARMv7s binary, then expect it to be different. Same case if one of the players took an update and the other didn't.

Even going beyond floating point issues, are the clocks perfectly synchronized? Are they running the game synchronously (i.e. slowly and in lockstep) and sending input to the other players every frame? There are a billion and one ways to mess up perfect synchronization, and I don't think it's generally worth it to try.