I'd definitely have to go for Mount and Blade: Warband, although Civ 5 is a close second. Surprised no one else has said the same. --- "You may not believe this, but I was once a remarkable man," -Denny Crane
Pretty silly question, I wouldn't bother investing/building/even care about PC gaming if I could only play a single game. --- Asus P8Z68-V LE | Core i7 2600K | 8GB G.Skill Ripjaws DDR3 | Gigabyte GeForce GTX 660 Windforce OC PS3 | PS2 | PSP| Wii | 3DS | DS | X-Box 360 | X-Box | NES
Minecraft. If I'm going to play only one game for the rest of time, it better be a game that I can have fun playing for the rest of time.
But, if I can still use my PC to play other games, then Skyrim.
I'd probably pick Minecraft as well, but not being able to use mods would make that a tougher choice to make. With mods, Minecraft. no contest. Infinite possibilities, so the game would take much longer to get stale.