On his blog Tiny Subversions, game developer Darius Kazemi posted a short article detailing the work he’s done to port the PC version of Spelunky to HTML5.
Kazemi also provided a link for those who want to play the port.
While originally the adventure game was made in GameMaker, Kazemi explains that YoYo Games released GameMaker HTML5 almost a year ago, allowing anyone to take a GameMaker game and “compile it to JavaScript so that it runs on a modern web browser.”
“In theory this should be a one-button process, but for a complex game like Spelunky it’s a bit harder,” he writes.
Kazemi provides a list of all the technical alterations and bug fixes he made for the port, including repairing rendering and making hard-coded hacks for bugs he couldn’t easily locate.
He explains that the process took him three hours, and that there’s still more work to do in terms of redoing “custom graphical effects” and locating collision issues that are difficult to reproduce.
In the meantime, you can enjoy a more-or-less complete browser-version of Spelunky.