They used a custom geometry engine to generate all textures at runtime based upon math instead of trying to store pre-rendered textures like most 3D engines work. Thus the huge space saving.
Some of their demos generate several GB of texture data.
The sound is provided via a MIDI and generated via a compressed code segment. No input system is needed, thus a space saving.
All code is finally compressed with a hacked version of UPX. Check out my UPX compression guide for more info....
http://www.xtremepccentral.com/modul...ticle&artid=30
Robert Richmond