Spelunky became a household name on XBLA in July 2012, it arrived on PC in late 2008 in its original low-res state. Source code for the original game was made available one year later, and just now received a new mod called Spelunky SD courtesy of Ukrainian developer Vadim. The mod adds, among other things, online cooperative multiplayer to the first version of the game.
In what started as a weekend project, the developer spent three months fine-tuning the mod for its first public release late last week. He tweaked the original game in a few ways, adding elements such as "sounds fading off-screen" or making enemies blink when they're about to get up off the ground. Vadim fixed a few bugs as well and made input precision "slightly more forgiving" in the game. The Spelunky SD mod is available to download through GameJolt.