This version had not a remarkable difference when comparing with Spectrum one. The game was released later for Commodore 64 because this machine had not a Z80 processor and for that reason all the assembler code should be rewritten. Spectrum, Amstrad or MSX code could be adapted more quickly because they had the same processor.
However, in this version there are some rooms that are different from the ones of other machines. We have seen two rooms at least, but it is quite possible that there are more. The explanation for this, according to Jon Ritman’s words, is that the 6510A processor (the C64 processor) has a lower performance than the Z80.