Highly competitive online Multiplayer
Shadowrun is the most in depth unique and competitive online shooter available today. If you've played counter-strike and loved it, Shadowrun is similar, but it adds magical and tech abilities which create an entire different dimension of play. Though difficult at first, the game is fun once you have the basics down. Any play who loves competitive online play needs to give this game a chance. There is nothing else like it.
The downside is that it is kind of limited. There are only a few maps and there will never be any expansions released. There are also only 3 game mode. Two based around capturing/delivering and artifact and one that is totally based around killing the other team. Unlike other games though the spells make it so each play is quite unique and this balances out the games problems.
This game can be found on New Egg for $10. It has also been cracked to run on XP even though the box states Vista only. On the PC version, unlike the 360, its free to play online and you play against 360 players so there are plenty of people playing all the time. The controls are well suited for a gaming mouse or a 360 gamepad. The graphics are also quite beautiful on the PC.