I remember seeing this demo and being really impressed - was determined to code my own. A friend of mine was already on the case and managed it before me - but I think my attempt was more precise.
aah - competitive days...
Affine mapping like this looks really crap for anything near the camera. If you are drawing a fine mesh (8mhz - hah!) you can draw 90%+ of the mesh this way but there are horrible perspective artifacts on the few that get up close. On an ST, most objects showed some wobbly artifacts.
The 'fix' was to use a near-isometric projection, damping the perspective just enough - but keeping the object big.
The other, similar thing that impressed me was the dithered gouraud cube on the floppy loader for 'Interphase' (the game). I even remember extracting the binary to have a look too