* SWAT 4: How cool is a multiplayer shooter where you actually have to breach a room from multiple sides to pressure the enemy into _not shooting_? And hold your guns until you saw any indication they would? We played that game for nights in one room for better communication.
* System Shock 2: Deeply flawed in some regards, but also the first game that creeped me out in a _perfectly well lit and bright environment_. Shodan, as always, was a great enemy.
* Freedom Force Series: A comic strategy game. It wasn't that hard (it wasn't easy, either), but had "comic" written all over the place. The description if you hovered the cursor over a mere building was "A proud participant of the Patriot City skyline." Someone put an ironic joke on the patriotic theme of the game in the description of a boring apartment block... How fun is that?
BioShock was a culmination of all that. Would you kindly pay them your respect?