One of the authors, Teri Li wrote the even earlier version published as a type-in program in The Captain 80 Book of BASIC Adventures and also wrote the C64 version.
It is likely that Mark Robinson implemented the graphics for this edition - yes, this is one bizarre case where the TRS-80 version has graphics and the C64 version does not.
The published solution for the C64 doesn't quite work for this version, as a few details have changed, but the two games are very similar.
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