What kind of map do you mostly like? Which kind?
Maybe an infection map would be nice. You are the Zombie and you need to infect the city. Basically there are 2 teams, 5 players each. Each player in the Zombie team will just have 1 Zombie. If you use an Ability like Bite or Infect to a civilian or someone, you control them. They vary on which kind of unit infected. Ex.: Civilian -> Normal Zombie, Soldier -> War Zombie, etc. All the non-Zombie team will just try to kill them. Has a First Person or maybe a Third Person Camera. Maybe the non-zombie team will play in an FPS mode.