I urge everybody to play the game first, at least ten times, before reading on. But you cannot fully appreciate the astonishing brilliance of its design until you have seen all of the surprises that have been built in. I believe this program is entirely faithful to the behavior of Adventure Version 1.0, except that I have slightly edited the computer messages (mostly so that they use both lowercase and uppercase letters). I have also omitted Woods’s elaborate machinery for closing the cave during the hours of prime-time computing; I believe John McCarthy insisted on this, when he saw the productivity of his AI Lab falling off dramatically (although it is rumored that he had a special version of the program that allowed him to play whenever he wanted). And I have not adopted the encryption scheme by which Woods made it difficult for users to find any important clues in the binary program file or core image; such modifications would best be done by making a special version of CTANGLE. All of the spelunking constraints and in