The mod, which is available for free from the developer, includes a number of fixes and improvements to the original game on top of its co-op mode.
"Of course, there are still more things that I would like to add to this," reads a statement from the designer. "It would be nice to allow the game to support more than two players. It would be nice to have a PVP mode (akin to Spelunky HD). It would be pretty great to get level editor and sharing back in, as well as some other forms of extensibility (to let the fun last even longer). Although right now a semi-distant dream, it would be great to have this work on Mac and Linux too (and maybe something else as well). And endless count of smaller things that matter."