"Our natural choice of language was MDL ... it is a descendent of LISP and is functionally extensible. It also permits user-defined data types, which is importa

"Our natural choice of language was MDL ... it is a descendent of LISP and is functionally extensible. It also permits user-defined data types, which is important in a game of "rooms," "objects," "verbs," and "actors." Finally, MDL makes it easy to imbed implicit functional invocations in data structures to tailor the game as described above. The initial version of the game was designed and implemented in about two weeks." For more information see: "How to Fit a Large Program Into a Small Machine or How to fit the Great Underground Empire on your desk-top" http://www.csd.uwo.ca/Infocom/Articles/small.html http://www.csd.uwo.ca/Infocom/Articles/small.html