The countdown sound does add to the experience, I agree!
Hmm ... hmmmmm .... in line 1, replace "D=1:IF...THEN..." by "D=MOD(INT(D)-1,4)+1". That's not exactly equivalent, but I think it does what you intended. And then you have enough bytes left in line 1 to replace "FORI=0TO127" by "FORI=0*RND(-4)TO127" or something? I am sorry, I could not resist ... just love these kind of puzzles, and had to do something similar for mine.
Thanks, those are both good ideas to save some bytes!
The reason I can't make the level look the same every time, is that the random numbers are used both for placing platforms and treasures, so even if you seed the PRNG the same every time, it will start to diverge when you pick up a different treasure. This could be solved with a second PRNG, but that's a bit of code, and you'd have to be mindful of the speed. Another idea would of course be to store level data instead of randomizing it, but that's truly not suitable for a one-screen comp. A third idea would be to use the program code itself as a sort of (bad) PRNG to generate the level...
