Bioshock 2

While on the surface it might look like little more than a very pretty first-person shooter, BioShock is much, much more than that. Sure, the action is fine, but its primary focus is its story, a sci-fi mystery that manages to feel retro and futuristic at the same time, and its characters, who convey most of the story via radio transmissions and audio logs that you're constantly stumbling upon as you wander around. All of it blends together to form a rich, interesting world that sucks you in right away and won't let go until you've figured out what, exactly, is going on in the undersea city of Rapture.

BioShock opens with a bang, but the overall plot focuses more on making an emotional impact than an explosive one. The year is 1960, and you're flying over the Atlantic Ocean. One mysterious plane crash later, you're floating in the water, apparently the lone survivor, surrounded by the flaming wreckage of the aircraft. But there's a lighthouse on a tiny island just at the edge of your view. Who in their right mind would put a lighthouse this far out? You swim closer and discover a small submersible called a bathysphere waiting to take you underwater. After catching a breathtaking view of what's below, you're sent into the secret underwater city of Rapture. Masterminded by a somewhat megalomaniacal businessman named Andrew Ryan, this city is driven by its own idea of total freedom, with capitalism completely unhindered by governmental meddling and science unhinged from the pesky morals of organized religion. 

Sounds like the perfect society, right? Well, even before you step out of your bathysphere and into the city, it becomes obvious that everything has gone horribly wrong down here. The city is trashed, and genetic freaks called splicers roam around, attacking anything that gets in front of them. At the heart of the matter is a powerful, corrupting substance called ADAM, which makes all this genetic tinkering possible and allows you to get your first plasmid power, the ability to shoot lightning out of your fingertips.

Minimum:
 OS: Windows XP SP3
 Processor: 2 GHz Intel Dual Core Processor
 Memory: 2 GB RAM
 Graphics: NVIDIA GeForce 8800/ATI Radeon HD 2600 (256MB minimum)
 DirectX «: 9.0c
 Hard Drive: 10 GB HD space
 Sound: DirectX 9.0c compatible
Recommended:
 OS: Windows XP SP3/Vista/Windows 7
 Processor: 2.3 GHz Intel Quad Core Processor
 Memory: 3 GB RAM
 Graphics: NVIDIA GeForce GTX460/ATI Radeon HD 5850 (512MB minimum)
 DirectX «: 9.0c
 Hard Drive: 10 GB HD space
 Sound: DirectX 9.0c compatible