Hmm well I was thinking it would have to have a strong replayable singleplayer, but since you say all other games get incinerated, if I pick just one online game, everyone would be playing it, so...
Sid Meier's Pirates!
Thief 2 (along with the mapmaking community)
aaaaaaand....
Battlefield 1942. Though Unreal Tournament 2004 was a close runner up.