Grand Theft Auto V
13 days 11 hours
Team Fortress 2
4 days 10 hours
Duke Nukem 3D: Megaton Edition
Wolfenstein: The Old Blood
Of course there's no Fallout news.
Fallout bows to Doom in all circumstances. Y'know, respect for your elders (and superiors) and all that.
Where the hell is Doom? (pardon the slight pun) Doom and Doom II are two of the absolute greatest all-around FPS ever, and they're still available.