I'm thinking of purchasing Portal 2...

[Donerail]

The only game worth buying is Starcraft 2. It's the only game I play.

lol

Go get Europa Universalis III

This. Or Victoria 2 if you prefer handling elections and economies to warfare. Both are really rewarding if you can get past the learning curve.

This. Or Hearts of Iron III if you prefer a more modern (gamewise, not development-wise) one.