The GameMaker source code for Mossmouth's retro-stylized subterranean platformer, Spelunky, is available to download from the game's official site.
Spelunky was originally released in 2009 for free on Windows PC and is currently still available to download from the Spelunky World website. An updated version, introducing overhauled graphics, two-to-four player co-op and deathmatch modes, hit Xbox Live Arcade last July. The new version of Spelunky is due for release on Windows PC this summer via Steam, GOG.com and Humble Bundle. Blit Game Studios is developing the PlayStation 3 and PS Vita ports of Spelunky, which are due for a worldwide release this summer.
For more about the roguelike, read our feature on the game's creator Derek Yu where he discusses Spelunky's journey from freeware to XBLA release. If you plan on picking up the title, don't miss out on our Spelunky review and survival guide.