[Fyron]

Not really. It depends on the design. The problem here is a client that actually executes most of the commands and sends the RESULTS to the host. 100% unbreakable is a design that only sends the commands to the host and does NO final data changes on client side.

And this is what SE4 does. The plr file contains ONLY orders issued, nothing else. All data files are read from the host's set when processing the turns. All game code is read from the host when processing. The player can only issue orders, not do any processing of anything. Unless he gets ahold of the game master password, in which case he can process turns on his own and see what will happen down the line, but the can not make changes to the "real" game the host sends out. The game detects even changes to descriptions of componetns and such and declares the data files invalid.