It is a set of libraries, tools and presets to create pixelated indie-style 8/16-bit era games in Javascript that runs in your browser without any Flash plugin, making use of a small small small subset of the HTML5 features, that are actually available on many modern browsers.
Another great HTML5 implementation idea. I seriously have to try to keep up with all the good new webdev stuff coming up these days, besides all my microsoft riddled day job fiddlings…