It's pretty amazing how much classic software can actually run, and works pretty well. The Wolf3D clone is totally playable, and you can actually use LSDJ (one of my all-time favorite pieces of software), and it seems to be actually running the real LSDJ, too, which is pretty impressive, considering that it means that the site actually has an embedded gameboy emulator

This is all HTML. You can inspect it.

Wait, so no emulation? Huh. Less impressive, but still quite so nonetheless.