Someone may have already suggested the idea of missions, so forgive me if I'm duplicating comments. One idea I had for a mission would be fleet defense. The ship(s) on each team would be directed by the game, i.e. non-player. Either the flagships have to reach a point on the map or the first team whose ships sinks loses the game.
There are all sorts of possibilities for mission-type games.
 "target practice"){kind=icon}
 "Sniper epic"){kind=icon}
 "The Bum"){kind=icon}
 "Windows Doors"){kind=icon}
 "Walk around a city and get lost in nowhere for beginners"){kind=icon}
 "PWNER-ECKSTREME-STURGEON-RAMPAGE-EVOLUTION version 2.0"){kind=icon}
 "Fly Or Die Multiplayer"){kind=icon}