These are what I consider to be the most important videogame first-person shooters in history. Some might disagree, but these are no doubt the biggies. Oh, and no sequels are on the list. That's cheating.
The original Halo game released the same day as the Xbox. Halo become a big hit in a large part to its split-screen and LAN network play, physics based vehicles, and it's composite, yet compelling sci-fi universe. http://www.xbox.com/en-US/games/h/halo/