I'm a big FPS fan but I really don't play games that much so about three years ago I made one commitment to finish three of the games that really defined the whole genre: Doom Half-Life Halo I know I'm several years late but here are some (short) comments about each of those: Doom I was lucky to finish Doom short after I made my commitment, I used Legacy Doom and my PC, awesome game. Man, the jump from the few levels of Wolfenstein I played is awesome, so many monsters on the screen, the levels are completely sick (specially the latest ones) and so many weapons! The final boss is a little boring thou. Half-Life One thing Doom lacked completely was a story, there was no narrative, it was all action. Half-Life you can almost say it feels like a movie, from the initial credits rolling while you get familiar with the controls to the very end. While the game is full of action there is a lot of emphasis on puzzle solving and adventure, a lot of jumps, you can really see why Portal was so famous, I mean the people at Valve can create some situations that while not impossible can make you think and say "ah!" before advancing, perfect balance of fun and commitment to the game. One thing thou the last levels are too difficult and are somewhat un balanced from the rest of the experience. I finished the PS2 copy, the best one based on the original engine. Halo The first time i tried Halo with a friend I almost puked, those ship levels with so many small halls and labyrinth-esque distribution were very de satisfying to play. I give it a small chance again just after I read the fist Halo novel, created specially for the game, well, now I see why this game was a console seller, from the balance of the weapons to the AI and even the graphics this game sweats quality in all fronts. A superb story telling is joined by an excellent and strategically challenged experience, Bungie IS one of the best developers out there. The magnitude of the levels really made me see why this type of game was never to appear on the PS2, it was just to gorgeous. Also, the last level is definitely heads and shoulders above anything that was on it's time, that was in fact the jump from old gen to next gen for FPSs. I finished Halo in my 360 last night. Well, again, I know I'm a few years late (in Doom, a few dozen of years). But for you what games do you think defined the genre or which ones defined the genre?