Oh man, only one game for the REST of my life? That's actually a pretty hard choice, but if updates/DLC/and all those things were included, that kind of narrows it down. I'm not much of a fan of World of Warcraft, but if I could only play one game for the rest of my life, I'd probably go with that. It's got a huge player base, hours upon hours of endless gameplay, new locations with each expansion and all that other good stuff. Seeing as I've only played it for a month or so, there's still an ungodly amount of locations, enemies, bosses, raids, and all that other stuff I haven't seen yet. So yeah, World of Warcraft would probably be the best choice for someone like me. Besides, with a game that big, you're guaranteed to make some awesome friendships as with any other huge MMO.