This is THE game that got Valve to be what they are now. The subject is a doctor in theoretical physics. Seriously, how could this game not be the definition of awesomeness?

Greatest game ever !

The story is amazing, the gameplay very flowing, the scripted events help alot to add suspense. Not to forget the multiplayer which is fun, too. But the FX could have been done better.

Perhaps the greatest shooter of all time. It says something when you can jump right into the game after blowing through the MW2 campaign and have more fun playing this 12 year old game. A masterpiece.

Back when it came out this FPS revolutionized the computer gaming industry not just because of the engine, but because of how versatile it was to help create mods for others - game is fun w/ good plot