6. Metro: Last Light
Metro: Last Light takes place in post-apocalyptic Russia, where you're trying to defend humanity from the Nazis. It's a deliberate, often painstaking game, but one that will reward patient players who marvel at the brutal beauty of this landscape. If the previous Metro games had flirted with becoming among the best games in the FPS genre, Last Light is the one that pushes the franchise over the top, for its combination of superb visuals, vastly improved AI and potent atmosphere make it stand tall with the Kings of the genre. There's a bleak grimness to this game that suits the apocalyptic tone yet is rare in video games; this is a mature, violent, hostile world in which you can be torn apart by any number of aggressors, either natural or man made, and the hidden Karma system ensures that you should best think before committing needlessly heinous actions.