Zombie DM
Basically, it's a team deathmatch extreme that starts with GMs on one team, and the players on the other team. When a GM kills a player, the player has to immediately switch teams and respawn on the other side. Now that the player is on the GM's side, it's that player's responsibility to help the GM's kill players. The last player to remain on the player side wins the point. This would be a game in which it would be most fun if the GMs didn't use instant kill weapons. Otherwise, it's just hide and seek with a team changing feature. Also, one obvious flaw would be that having to reset the teams at the end of the match is a pain.
But what do you think? Fun?
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EDIT:
I just realized that once a winner is claimed, the winner and the GMs can easily switch teams and play again from there!