What to play?

Yea.. a picture of all your games... hard to know what you have for kinds of game :)

Since you already have 10+ hours in Sotmc, got some Revelations going on.

Some games you could try finishing maybe?: Alan Wake, BioShock, F.E.A.R., Red Faction: Guerrilla, Prototype.
EDGE and Jamestown are very nice too.

the answer to all your worries.

Shatter!

Great take on Breakout, with an amazing soundtrack!

Mafia II of course.

Go play Mirror's Edge!

Psychonauts. Finish dat game.

Xcom

Reccettear

its not on steam yet but cook serve delicious is pretty fun.

if you are just looking for suggestions from what you own.

Hitman Blood money, you have less than an hour in this amazing game, correct that mistake.

battlefield 3

The binding of Isaac / Audiosurf

Revelations 2012!

You have quite a backlog, why not try a game you haven't played yet? :D

finish stalker, farcry and armaggedon for the love of god D:

get more time into Borderlands 2...

Get more time into Fallout 3 and New Vegas :L

so many games and money wasted...

Hitman: Blood Money and Super Hexagon are both excellent games. I recommend Super Hexagon, but Hitman might be more accessible.