Not a commentary on this project per se, but I can't help but think when I see "X in javascript" voted up that the implicit frame is: "isn't it impressive what you can do in javascript now?" But if you flip that statement on its head, the equivalent is "The web has finally caught up with what we could do on a 1997 desktop!"
The next logical step is Diablo in CSS3.
Of course, it's much harder to do a game in pure CSS, like this crazy thing http://jsdo.it/GeckoTang/4rXg