Some of the biggest and best games available via the Mac App Store have seen some big reductions today, with BioShock 2 down to just $12, and Call of Duty 4: Modern Warfare, Star Wars: Knight of the Old Republic, Galaxy on Fire 2, and Tomb Raider: Underworld down to less than $10.

Galaxy on Fire 2 is perhaps the best-looking space game on iOS. With astronomical scenes that call to mind a portable Eve Online, Galaxy on Fire 2 is an action space shooter with RPG elements, such as upgraded ships and weaponry, questing systems, and the like. It’s even made the move to Mac OS X.

It’s been a couple of months since FishLabs, the developers behind the title, released a teaser trailer and a vague September timeline for a release date for the upcoming downloadable content (DLC) expansion, Supernova. Well, that date is actually here, as Supernova is available on both the iTunes and Mac App Stores, for iOS and Mac OS X, respectively.