Priced at $10, "Mad Moxxi's Underdome Riot" brings the new "Riot Mode" into Gearbox's shooter-RPG alongside three dedicated Riot Mode arenas, a few more skill points, and a bank that provides extra storage space for items. Similar to Gears of War 2's Horde Mode, Riot Mode has players facing off against ever-increasing waves of enemies.

As with the Xbox 360 version of Mad Moxxi that hit just before the new year, PlayStation 3 owners need only navigate to their console's respective online marketplace for purchasing details. As for PC, those with the retail Borderlands DVD can buy the content direct from Gearbox, with Steam selling a version compatible with copies bought through its digital distribution service and others expected to follow.