Hexcells Complete (3 copies, for level 2+, open for 7 days) http://www.steamgifts.com/giveaway/OLBjn/hexcells-complete-pack This game was my surprise of the year. It's the best puzzle game I've played in ages, and I can't believe I hadn't heard about it before this!
Hexcells is like Picross mixed with Minesweeper. I recommend it for anyone who loves deductive logic puzzles but wishes they weren't so wordy and for anyone who once loved minesweeper but wished you never had to guess at the next move. It starts off very simple, but some of the later puzzles took me hours to complete with no mistakes.