...as Quake is to multiplayer 3d shooters. Revolutionized the genre.
(Side note: There's no excuse for MULE not to be on that list - there are games older than it on the list.)
Here are games that IMO don't belong on that list, and why:
Unreal - Yeah, it's pretty. Quite frankly, the single player didn't do much for me. The AI was overrated (It's basically Quake/Doom level AI, except the critters move a lot faster, do a lot more damage, and take a lot more damage. The deathmatch bots were pretty good, though.) and the story made no sense (to me) whatsoever.
Halo - I've already said why.
I'd replace them with StarFlight, and Fallout/Wasteland.