What really sets this game apart for me is the firmly grounded sense of place. This game isn't afraid to use SF tropes when it makes sense--energy shields, anyone?--but it will just as quickly abandon them when they seem silly or out of place. No silly laser pistols here, you get guns. Fancy future guns, but still, guns.
The alien races introduced here can seem at first glance like they came from the Planet of Hats; the Turians are Proud Warrior Race Guys, the Krogan are uncultured barbarians, etc. etc. Nevertheless, the game spends plenty of time fleshing them out, to the point where I stopped reacting to them as stereotypes, and started treating them like people; crazy, silly, infuriating people, but people nonetheless. That, aside from anything else, sells the game for me. The huge, explorable galaxy littered with wonders both natural and sapient-made just puts icing on the cake. Mass Effect is what Star Wars tried to be and failed.

Have you ever played Torchlight or Diablo II and found yourself thinking "I wish I could skip all this loot grind crap and just get to killing monsters faster"? If so, you may like Magicka. No potions here, no Scroll of Town Portal, no sitting there shuffling your inventory to stuff in one more +1 Dagger of Vendor Trash. Just fast, furious action, with a dynamic spellcasting system that rewards experimentation. The humor is decidedly Pythonesque, with more nerd-pop-culture references than you can shake a Staff of Blasting at. Both adventure mode and the challenge modes can be completed with up to three of your friends, and when you're tired of blowing each other to bits accidentally, you can blow each other up intentionally in the recently added Versus mode. Great fun, and probably the best $10 you'll spend on the Steam store.