Unfortunately there's not much information available on the site, so any technical details will have to be found in the source code. The page does mention that he's using ExCanvas to make it work on IE, but that's about it.

The demo itself is pretty simple, you just walk around a pseudo-3D maze. There's a bit of gun-wobbling and some jumping thrown in as well. In the default mode, the walls are rendered as single colored surfaces but there's also a textured mode which, even if it's much slower, shows that there's potential for Wolfensteinish action.