Ive really enjoyed it the past few days but holy hell is it hard. There is no f'ing around.
I first completed it on a totally unexpanded A1200. You'd get pasted in later levels where the frame rate became unbearbly slow and, after a couple of attempts, you'd depend your foreknowledge of what was around each corner in order to simply make it through.
Alas, TKG on the 040 was not quick either. However, I did mod the living daylights out of it later when I figured out how the editors worked. I never really created any new levels, just modified the existing ones, adding new areas, textures models etc.
Somewhere I still have that mod. I was particularly pleased with my chaingun and grenade launcher models (the latter had a rotating clip that was also used as a model for the grenade pickup).