On 2012-02-01 I wrote to Don Woods (in a postscript to a production update
on Colossal Cave: The Board Game):


  By the way, I just noticed last week that in “Adventure”, in the Hall
of the Mountain King, the directions NORTH and LEFT are synonyms, as
are SOUTH and RIGHT… as are WEST and FORWARD!  West being forward
makes sense, if the Hall of Mists is back to the east; but for the
rest I suppose the adventurer must be walking on the ceiling. :)  This
little mixup is present all the way back to
Crowther’s code.
I just thought it was funny that nobody had commented on it before, as
far as I know.

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Arthur O'Dwyer

A historical note about a directional inconsistency in the classic text adventure game 'Adventure' (Colossal Cave). In the Hall of the Mountain King, NORTH/LEFT and SOUTH/RIGHT are swapped synonyms, while WEST/FORWARD is correct. This bug traces back to Crowther's original code. Don Woods confirmed he noticed it and fixed it between his version 1 and version 2.5. Various other ports of the game preserved the bug unchanged, while a couple eliminated it indirectly by simply not recognizing LEFT/RIGHT/FORWARD as valid exits from that room. A related directional bug in the Wellesley Adventure port is also noted.

Adventure: Walking on the ceiling