If you're looking to pick up Civilization, Mafia or some of the XCOM games on the cheap, this is a good way to go about it.
Running for the next few days, the bundle will give you a 80%, 83% and 85% discount if you select three or more games. If you just want one or two games, you'll get a 75% discount.
Here's the full list:
Bioshock: $4.98 Bioshock 2: $4.99 Duke Nukem Forever: $4.99 The Stronghold Collection: $7.48 Civilization Beyond Earth Rising Tide: $7.49 Mafia 2: $7.49 Battleborn: $7.49 The Bureau XCOM Declassified: $7.49 Spec Ops The Line: $7.48 Bioshock Infinite: $9.99 Civilization Beyond Earth: $9.99 Darkness 2: $9.99 Borderlands 2: $9.99 XCOM Enemy Unknown: $9.99 XCOM Enemy Within: $12.48 Borderlands GOTY: $12.48 WWE 2K16: $17.48 Civilization 5: $17.48 Borderlands The Pre-Sequel: $17.49 Civilization 5 Complete Edition: $19.98 Borderlands 2 GOTY: $19.98
(The expansion packs for Civ 5 are available as well, but at more than $US12 a pop you might as well just grab the Complete Edition instead.)
If you're looking for some of the older titles, like Darkness 2 or Spec Ops: The Line, the bargains aren't too bad. 2K doesn't have any discounts going on Steam right now, and a sample bundle I put together with Spec Ops, Mafia 2 and Bioshock 2 came to ~$21, which isn't too bad for three solid games.
You can check out the bundle for yourself here.