It would be a game made for multi-play. There can be up to 4 teams, and each team controls a building, there base. The object of the game would be to over run the other team's buildings. There would be 2,3, or 4 buildings, and when you over run a building, you can pick to spawn there. Different buildings would have different upgrades for: weapons, vehicles, and security systems. When you kill a member of an enemy team, you get money, more money if the player has a higher score, lower if they have a low score. this money goes to the Teams bank, which the team leader can use to buy upgrades. When you over run a building, you get the upgrades the team had before. When a team over runs a building, players can choose to help the team that took over (they turn to that team) or they can quit.
I think it would be a fun X box live game