All 2K games are on discount today til Sunday.

I'm definitely purchasing Bioshock and Bioshock II for $20 but waiting until Sunday in case they come up with an even better deal. I really liked Bioshock, and have yet to play Bioshock II.
http://store.steampowered.com/app/76...r=1_4_4__106_1
http://store.steampowered.com/app/8850/?snr=1_4_4__106

I'm feeding my addiction interested in purchasing:
Mafia II Digital Deluxe Edition plus all the expansion packs for less than $20 bucks.
http://store.steampowered.com/app/50460/
Stronghold Collection. I've played Stronghold II after purchasing it from GOG and had a little mini addiction, but the game was difficult for me to play. I've heard Stronghold III is not worth purchasing(not included in this package), but the other games in the series are worth some time.
http://store.steampowered.com/app/90...r=1_4_4__106_1

Games I already own:
Civilization 5 plus most of the expansion packs are on sale in the Game of the Year Edition for $25.
http://store.steampowered.com/app/90...snr=1_4_4__106
Korea and the Ancient Wonders of the World are the only two missing and can be purchased here for $4.
http://store.steampowered.com/sub/11..._7_suggest__13
A lot of homework was rushed to finish back in highschool when I first started playing Civilization III. I spent a lot of afternoons lost in conquering virtual civilizations. I missed out on what I hear the great game is Civilization IV. Civilization V I have seen mixed reviews, but IMHO, this game is fun to play. I think the world map looks great, no more stacks of doom via one unit per tile, and changes from square to hexagonal movement add to the strategy. If you haven't played this recently, the AI has improved tremendously but any (heavily addicted) Civ veteran can still overcome the odds.

Duke Nukem Forever and Expansion packs are also on sale. I already this and still need to play.
http://store.steampowered.com/app/57...r=1_4_4__106_1

Other games I see worth mentioning are Borderlands plus all expansion packs as well as Civilization IV plus all expansion packs. They're part of the 2K sale. =

Also, this has nothing to do with the 2K games sale, but a worthy mention would be the Double Fine Bundle.
http://store.steampowered.com/sub/13...r=1_4_4__106_1

I' already own it, but if you're looking for a fun experience get Psychonauts. I've heard good things about other games, but Psychonauts is an amazing action/adventure platform-esque game. This game is the brainchild of Tim Shaffer who is famously known for designing and writing for The Secret of Monkey Island, Day of the Tentacle, Grim Fandango, and Brutal Legend.