from my recollections forever ago, RTS games like the spring engine use checksums on state to prevent manipulation.  the game client gets &quot;out of sync&quot; if a client&#x27;s checksum doesn&#x27;t match.  The state checksum is computed at every tick of the simulation.  This makes it so you don&#x27;t have to run the simulation on the server.  Debugging is very hard though, and odd things like FPU precision on different processors can create all kinds of difficult bugs.