This story was written in 2 parts as it mentions a ZorkQuest no. 3 (that was never released) in the last "panel".
Infocomics were a huge commercial failure for a number of reasons:
ZorkQuest: The Crystal of Doom was released after the original 3 Infocomics flopped. Since this one was "in-the-can" it was shipped, but to save costs, only the cover art was changed, the rest of the package was the exact images from ZorkQuest: Assault on Egreth Castle.