It's commonly theorized that the castle is a physical manifestation and representation of the A.I., which personalizes and adapts Super Mario 64 to the player's desires. The castle's intricate and bizarre layout could be a result of the A.I.'s intricate inner workings, with the castle's very walls and rooms representing the A.I.'s vessels and nerves. This hypothesis is supported by a former developer's anecdote about the fabled 1995/07/29 build of the game. Here he describes that the basement of the castle was used as a testing ground for the A.I.'s ability to adapt to players, creating an endless labyrinth for players to run through. An unfortunate playtester was apparently driven insane by endlessly wandering the basement. The fact that the castle now appears bigger in the retail copy only implies that the A.I. has grown more since the 1995/07/29 build.
