I always loved Sauerbraten's anti-cheat mechanism. You could hack the engine like swiss cheese, add console commands to kill any player you like, shoot projectiles that only monsters could. Each server had an admin slot which could be claimed if empty. As long as someone cool claimed the slot, they could kickban cheaters.

On the other hand, when people did coop-edit mode, a lot of people would toggle and fuck around because there was nothing at stake.