What about an "inside man" mode, where a thief can choose(or corrupt) a guard to be at his side, and no one of the guards team could know who is the traitor. It would be useful in this kind of mode a whisper mode, where you could talk just to one player. Hope you like the idea! btw game is very cool, and pretty addictive as well!
 "Of Guards And Thieves"){kind=icon}
 "Sands of the Coliseum"){kind=icon}