There are quite a few games out there that hypothesize the consequences if the Cold War had turned into a hot one. In the RTS genre notably, titles like Wargame and World in Conflict portrayed scenarios where Soviet and NATO forces faced each other head on. Metro parted from a similar idea.
The backstory of Metro 2033 is one where Russia, presumably along with the rest of the planet, is now suffering the consequences of the aftermath of nuclear warfare that took place two decades earlier. You play the role of Artyom, one of the survivors of the initial onslaught who sought refuge in one of the subway stations of Moscow. As a member of the underground community, you venture beyond the safe zones to advance the storyline and battle both rival human factions and mutants alike.
Metro's story is not just one you should play because of the interesting post-apocalyptic setting (the Fallout franchise fills in that checkbox pretty well too), but because the perspective of playing as a Russian is rare enough, and playing as a Russian survivor in a post-apocalyptic nuclear world is absolutely unique in itself. The story and gameplay developed by Eastern gaming enthusiasts 4A Games gives us a significantly different experience from the more Hollywood-ish franchises developed in the West. The game was such a success in both Russia and the Western market that the third title of the franchise is currently in development and set to be released later this year.