Not really an unreleased game, but some bits and bobs that could be nice to save if they still exist.
Looking at the preview screens in Zzap for the 3D Construction Kit, as well as an earlier editor kit, there is a hospital ward scene using a very early edition of the editor. Both Andrew Fisher and Robin Gravel confirmed the hospital scene was from Castle Master (which may have been a demonstration of the tool’s power)
As I cocked up with the Castle Master inclusion, I may as well add the CF office screens that were produced. No doubt long gone and just done quickly to accompany a review.