Far Cry 3: Blood Dragon. I didn't realize till I downloaded it that it is a completely separate game, so you don't need Far Cry 3 to play it. And you should play it. If your upbringing involved the 80s, terminator, aliens, or any other crazy 80s action sci-fi, then you should play it. The main character is voice by Michael Biehn for cry'n out loud.
If you love things awesome, cool, and perhaps at one point even radical, then I highly suggest this. Jokes everywhere, and the music and visuals are just perfect.
I feel like I'm playing one of the robot war scenes from terminator when I play this game.