Well, the game won't let you back in for 15 minutes at the least. Once upon a time, computer time in universities was very scarce, and this was the author's way of gently encouraging you go go outside and get some fresh air. But nowadays it's just a big pain.

After 15 minutes, the game will let you on, if you are a "wizard." The wizard's password is "dwarf." Non-wizards have to wait 45 minutes before they can play again.

There is some indication in the game program object file that there is a provision for setting holidays and certain hours in which the game can or can not be played, also, but I don't know anything further on this.