It would be like a normal game, but there is an overall time limit. Say at intervals of 5, 10, 15, 20, 25, 30, 35, 40, etc.
If I need to go soon but want to play a quick game of VW I could just set the time limit to say...10 minutes. If I happen to beat them all within 10 minutes, so be it. But, if it does last to the end of 10 minutes the winner(s) will be decided on a number of variables (such as amount of territories conquered, finishing blows, etc.).