On 2012-12-01 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.

Don Woods wrote back the same day:

Yes, I vaguely recall finding that at some point.  It was wrong in my version 1 but got fixed somewhere between there and my version 2.5.

Indeed, where WOOD0350 has:

19    311028  45  36   # 45=N 36=LEFT
19    311029  46  37   # 46=S 37=RIGHT
19    311030  44  7    # 44=W  7=FORWA

WOOD0430 (his expanded Adventure 2.5) has:

19    311028  45  37   # 45=N 37=RIGHT
19    311029  46  36   # 46=S 36=LEFT
19    311030  44  7    # 44=W  7=FORWA

The original inconsistency is preserved, without comment, in KNUT0350, GIBI0375 (Original Adventure), LUPI0440, PLAT0550, LONG0751, and SMIT0370 (Georgia Tech FunAdv).

ROBE0665 (Wellesley Adventure) and ARNA0770 eliminate the inconsistency — albeit not in an obviously purposeful way — by simply not recognizing LEFT, RIGHT, and FORWARD as exits from the Hall of the Mountain King.

ROBE0665 has a superficially similar slip-up at Three-Opening Arch:

265     To the east stands a wide dark arch opening into three
265     passages.  All lead eastwards; but the left-handed passage
265     plunges down, while the right-hand climbs up, and the middle
265     way seems to run on, smooth and level but very narrow.
265     To the north of the great arch stands a stone door, half open.
265     To the west the passage fades into darkness.

265     0 66   LEFT  NE UP
265     0 34   RIGHT SE DOWN
265     0 273  EAST

Here LEFT correctly matches NE, but goes UP where the room description says “plunges down”; and RIGHT correctly matches SE, but goes DOWN where the room description says “climbs up.” I reported that bug to Eric Roberts on 2025-04-23, although at that time I don’t think I’d noticed that LEFT and RIGHT actually worked correctly in that location, and that it was only the UP and DOWN directions that were wrong.

See also:

• “A bug in Adventure’s endgame” (2020-02-06)