Copenhagen-based independent developer Playdead announced today that atmospheric downloadable puzzle platformer Limbo has passed 1 million worldwide sales, and that a Mac version of the title is in the works.

Limbo originally launched as part of Xbox Live's Summer of Arcade in July of 2010, selling over 580,000 copies by the end of 2010, according to a Gamasutra analysis. PSN and Steam ports for the game were released this summer.

Alongside the sales announcement, Playdead revealed a Mac version of Limbo will be released "before the end of the year." Playdead CEO Dino Patti told Joystiq the Mac version would be available on the Mac App Store and Steam, with SteamPlay support enabling a seamless transition for PC players.

Limbo's sales success recently allowed Playdead to purchase itself back from investors giving it more creative freedom as it works on an upcoming Unity-powered title.

"We are grateful to everyone who supported us over the past few years, and look forward to forging new partnerships that will both let us reach new heights as a studio and give our director, Arnt Jensen, room to grow creatively," Playdead CEO Dino Patti said in a statement.