The history of the game Zork is a long and winding one, starting with MUDs and kin on university mainframes – where students entertained themselves in between their studies – and ending with the game being ported to home computers. These being pathetically undersized compared to even a PDP-10 meant that Zork got put to the axe, producing Zork I through III. Originally distributed by Infocom, eventually the process of Microsoft gobbling up game distributors and studios alike meant that Microsoft came to hold the license to these games. Games which are now open source as explained on the Microsoft Open Source blog.