Anyway, did you try to change Zorn's lemming to require you to get up higher already? And another thing, in the old forum I found a not-working link from you to a 'Hard.zip', is it possible to get that anyway? Finally, if you need any help on whatever, feel free to ask me whenever you want and I'll try to help.
I've been too busy with my dissertation and Repton 3 lately to have much time for Lemmings this last month... now the dissertation is done I should get back to Zorn's Lemming, that one had the potential to be a nice level.
"Hard.zip" was an early collection of ten levels: Have a bash at this!, Rockabye Baby, Bound for Lemming Heaven, The Crystal Maze, Down Among the Dead Lemmings, Lemming Dilemma, Up on the roof, It's all about survival, The Simultaneous Display, Lemmy out of here! They were my first efforts, and naturally ccexplore and Insane Steve found tons of backroutes, so when I did my new styles I set about converting the easiest-to-de-backroute ones first, which is why some of those have since turned up in my later sets while the others are still on the drawing board.