Hey, here are some old and new game mode ideas I've thought of.
Intel: There is a laptop somewhere in the map. The objective is to grab the laptop and hold it for as long as possible. The laptop carrier location isn't revealed unless a UAV is up. If he is spotted then his location is revealed.
VIP: Pretty much an assassination match. One team has to take out one member of the other team. Team version of Assassin.
Informant: There is a hostage on the map. Your team must grab him and bring him back to your base. There are two ways to carry him. One is carrying him on your shoulders and which means you are defenseless. The other is putting your arm round his neck and pointing a one handed gun out. If a team kills the hostage then the other team gets the point.
Assassin: Everyone is assigned a target. Note the assassin and the target aren't the same. You lose points if you shoot a non-target, however you won't if you shoot your assassin. Tense gameplay is assured as you try and hunt your target without being taken out yourself. Wager match perhaps?
Super Soldier: This is a free-for-all type mode. At the start, everyone have their classes. But when someone gains the first kill, they become the super soldier. They gain Death Machine/ Grim Reaper and 300% health. Everyone else wants to hunt the super soldier. There are no points gained or lost for shooting other players.