I have found a dissembley of the Atari ST version. It looks like alot of work to convert to the QL. There is much use of the hardware Blitter chip, which the QL does not have.
Could a software blitter routine be fast enough to perform the block transfer of data in parallel with the CPU operation?
The Minerva fast memory move vector could probably achieve this. Assuming the routine could be multitasked.
Strange because I had it on my 1040 SFTM (that haven't the blittter) and works well
So I think It was programmed for use it on a Blitter ST (MEGA ones) but also with others than haven't it (520ST, 520SFT, 520STFM, 1040STF, 1040STFM).
I remeber that when there was many "sprites" on the game is slows a lot.