I propose something like the following for the first person to leave any game;
1st turn leave is ban from atwar for 1 day
2nd turn 12 hours
3rd turn 6 hours
4th turn 3 hours
5th turn 1 hour
If someone waits 6 turns to troll well joke in on them since they wasted 20 minutes of their own life which is pathetic.
If you try to leave there should be a warning message "Are you sure you want to leave this game? You will incur a temprorary ban from atwar for x (days/hours) for this action."
Every time you leave again your ban is doubled in time, which resets every month. So if you first turn leave another game in the same month ban goes up to 2 days, then 4, then 8, etc.
EXCEPTIONS to this rule are;
1. someone has already left in the first 5 turns, you can leave with no ban since game is ruined
2. You are the only person in the map or scenario (ie: testing)
People say they have "got to go" a lot of the times when they leave, so if you REALLY "got to go" then you won't care about getting banned from joining other games since you are not on atwar. Most people just first turn leave so they can join the latest RP