That's an awful list IMO, doesn't even have one single MGS game... THIS IZ MADNESS!
But it's kind of understandable: IGN just didn't want to chose an exclusive game of the current generation (360/PS3/Wii) and put it on the top 3 because that would generate too much controversy, for example: if they chose Killzone 2, 360 fanboys would be like "OMFG WEHRS HALOZ", if they chose Gears of War 1, PS3 fanboys would rage all over the website and make a petition to replace it for Uncharted 2. [I'm aware that U2 is on the top10, but I got make fun of ps3 fanboys as well :P]
And what websites like IGN should stop doing when they decide to make tops like this, is giving a numeral position to games. I wouldn't mind seeing Half-Life on a list of the best games of this decade, but saying that's the best game of the last ten years makes me lol
P.S Not even one hack 'n' slash, racing, fighting game in that list?