Borderlands
Pandora is a down-and-dirty mining planet that resembles a trashed, irradiated version of the American Wild West. Your job is to scour that landscape in search of the Vault, a semilegendary cache of technology and wealth. This mostly involves collecting an astounding variety of bad-ass guns and tooling around in funky dune-buggy-type vehicles with really bouncy suspensions while blowing away deranged and mutated bad guys. Borderlands is a marvel of hybrid game design: you add levels and skills as in a role-playing game, but you're doing it in a sandbox-style open world while engaging in run-and-gun first-person-shooter combat. Add in astounding graphics and wickedly clever writing, and you have something that's about as close as you can get to a perfect game.