Therefore, its known narrative elements are not a part of the Doctor Who universe as we, on this Wiki, choose to define it. It may have been the basis for a similar story in another medium, however — and that story may indeed be valid.
The Castle of Doom was an unproduced story written by David Fisher for Season 18. Fisher submitted this storyline to producer John Nathan-Turner on 7 November 1979. Nathan-Turner rejected it in favour of developing The Leisure Hive. (REF: DWMSE 9)