There are currently like 3 game modes: DeathMatch, King of the Hill and Crazy King. The latter 2 are less popular amongst new players - you can see how many people leave lobby after The Labyrinth pops up.
What I suggested during last dev fireside was the "Time Battle" mode, where players try to destroy as many enemy ships as possible during i.e. 15-minute game.
It's perfect for people who don't like CP games, for competitive games and good against long sniping matches (these will still work in standard deathmatch).
It's also super easy to implement.