I think it should be like rocket Arena for the Quake series.
That would mean that you have several arenas, with different styles, on one map. There are 1on1 and team arenas. The player can jump from one arena to another at any time. If an arena is already occupied, he can choose to:
- wait in line to fight, while spectating
- just spectate, without fighting
- change to another arena
In our case we could add:
- spectate and place a bet