Orcs Must Die 2: This game is a lot of fun, especially with a friend. For $3.50 you can’t go wrong.
Mark of the Ninja: Fantastic stealth game. I’ve played it through fully 3 times, and it’s $3.50!
Sleeping Dogs: I’m playing this game right now (having picked it up 66% off.) It’s now 75% off. It’s GTA with kung fu. Well worth the money.
Chivalry: Team Fortress with swords. It works a lot better than it sounds. I’d recommend grabbing it while on sale. Currently 50% off.
XCOM: This is 50% off. It’s pretty criminal if you don’t have this already. With a deal like this you simply can not pass that up.