Battlefield to the Future!
Basically Battlefield is a similar premise to Counter-Strike, its a Multiplayer only gameplay, there is a single player element but its just the same with bots.
Battlefield 2142 is a standalone game as aposed to counterstrike which is a mod for half-life. Battlefield 2142 is a really simple premise that has never changed, there a number of bases on the maps, you travel to the base, stick around inside the base area, a meter goes up as you capture that base, you get points for doing so, and defending against invading enemy and points for taking bases.
Its really simple and really fun, made better by vehicle play and all the different weapon classes. Titan mode is same idea, but when you capture the bases, a Missile is launched from it and it goes into the shields of your enemy titan, which is a big floating air-craft carrier ship thing. Both teams have one, the match starts by taking bases, the more bases, the more missiles you have attacking your enemies titan, once the outside shields are down on the enemy titan you can fly upto it and board it. Once inside you can blow up 4 consoles to gain access to the core of the ship, then you destroy that and get the hell off the titan right before it blows up or you blow up with it. The titan mode is fun because there are always big fire fights in the titan corridors as the enemy defenders work hard to stop you attacking.
You should deffinatly get this game, I would recommend it to EVERYONE.