Replay. The sequel to this is one of the most absurdly fun games I've ever played. It's tonally all over the shop but always entertaining; almost like Yakuza in its blend of the serious and the ridiculous. This isn't quite as nuts as the second game, but it's still an absolute blast. And dang, the visuals really hold up -- hard to beleive this is nearly a decade old.

Replay.

Halo 3 marked the peak of Xbox as a brand, for me at least. Although I never actually owned a 360 in its heyday, I did borrow one to play this -- and it delivered on the hype and then some. A brilliant campaign. Still plays like a dream.