It's based on work by Jim Gillogly, who had produced one of the earliest (and authorised) ports of the game to C/UNIX. Jim convinced Software Toolworks to make a royalty payment to Crowther/Woods for the use of their work; making this one of the only commercial releases of the game for which they received payment.
There are several editions of the Software Toolworks version.
A listing from the Software Toolworks Summer '82 catalog lists the game as being available for Heath/Zenith machines, 8" CP/M systems and Osborne 1. The game's manual mentions the game runs on Z80 and 8080 systems with at least 48K, with versions supplied for CP/M and HDOS.
Later adverts list the game as being sold for DOS PC, such as that in PC magazine, December 1982, p. 339, where it is being distributed by Norell Data Systems, and is billed as "the only official adventure game endorsed by Willie Crowther and Don Woods". It's also mentioned in Norell's list in Softalk December 1982.
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This is GIBI0375 in the Adventure tree taxonomy. A slightly extended version of the C&W original adventure, with a small amount of added content. The new puzzles are very much in the spirit of the original and the ending is more satisfactory. There are 17 treasures in the caves, and the two of them new to this version are tricky enough to find. A well debugged, polished variant (for 1982 standards).