They are or have been distributed by CDS.
Castle BlackstarType: Text only Written 1984 by Mark Shepherd, Mike Redman, Andrew Cummins and Richardson.
Notes: It has a screen layout similar to Infocom with status line and location titles. The game has a 200-word vocabulary. A 'modest prize' was offered to the first few players to complete it. Planned to be the first in a series of related quests.
Comments: The objective is for you to find and get rid of an evil orb (!) whilst locating treasures along the way. Very entertaining.
Here is a review of Castle Blackstar
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