Its always a pleasure to mess around in Spore.

I would say go for Deus Ex (the first one being "The Conspiracy") If your computer doesn't have too many graphical glitches, and you can get through the first level, you should enjoy it. Everyone that I have heard has played it either loved it, or didn't get through that first level, which is Liberty Island.

ACII. Loved that game.

Trine. It's a quick but charming game. You can knock it out in short order and move on.

Two Worlds : Epic Edition !

Fable

legendary

Spore

Dead Space 2

Max Payne

Trine

STALKER... Play S.T.A.L.K.E.R.: Shadow of Chernobyl... NOW! Best game ever.

Dead Space 2 and Bioshock 2 I really enjoyed both, but you have a lot of other tempting games to play first

Dead Island. My copy went untouched in my library for a long time. Before I knew it I was 80+ hours in.

F.E.A.R.

Dead Space 2 :)

Prototype

Damn, wish I had such a small backlog :(

Fable - The Lost Chapters!

Mass Effect

First world problems... I personally vote for Dead Space 2 or Mass Effect (both are one my favourites).

I'm going to say 25. Payday the Heist. Even if you haven't tried it put an hour into it, It's an amazingly good game, Fast paced and gets you thinking, A 20 minute Heist seems like an hour and it's amazing with friends :D

Dota 2, if you dont have i will give you.