Feral Interactive is having a huge sale for BioShock and its sequel, BioShock 2, for 50 percent off from August 23rd through September 2nd. You can pick up either game from the Mac App Store for $10.
The original BioShock won awards and the adoration of gamers for its intense first-person shooter design. You find yourself in the undersea world of Rapture, a libertarian utopia that's been perverted into a horrifying mess thanks to rampant genetic engineering and other things that have driven Rapture's residents mad. The sequel picks up in the same location, but later, and with an entirely different set of characters and challenges. Neither are to be missed.
BioShock Infinite is also in development, though not by BioShock I and II's Mac publisher Feral Interactive - Infinite is being worked on by Aspyr and is expected to be released next week.