Borderlands 2

Ari: No question, Borderlands 2 should be considered up there alongside Mass Effect 2 and Uncharted 2 as one of the best-ever sequels in video games. It took a plainly ridiculous premise—treasure-hunting your way through the cosmos—and turned it into something real, with stakes and compelling characters and, as Zack mentioned, a ridiculously strong villain. It expanded the lore in a way that felt natural. And it did it all without losing a grasp on the charm and humor that defined the first game.
Zack: Same.