I know this has been a *looooooong* time coming, but I have finally been able to make the source code for this game available. The repository is at the following location:
https://github.com/TheGreatGallus/Cavern-GB
Sorry for the incredibly long delay. Life got crazy, then my desktop was in storage for over two years and I had no access to the code until a short while ago, and I just got around to getting it set up with a repository.
Hopefully someone will find it useful (even if it may be a bit outdated at this point...)!