Amazon is bundling together three of Firaxis Games' most recent at a really low price. For $20, you can snag PC download codes of XCOM: Enemy Unknown, Civilization 5: Gold Edition – a definitive version with Gods and Kings and a bunch of other DLC – and Civilization 4: The Complete Edition, also including a host of DLC and extra goodies.

The Firaxis bundle headlines Amazon's Digital Mayhem promotion, with other discounts spanning Telltale's The Walking Dead, Battlefield 3, BioShock, Mark of the Ninja and many more. The sale ends on May 31, so feel free to take your time perusing the hundreds of eligible discounts.

This article was originally published on Joystiq.