Adventure in the Fifth Dimension

Mostly written in Atari BASIC (with a hint of 6502 assembly), this game was
Brian Moriarty’s first text adventure. Its player controls a private
investigator on the trail of extra-terrestrial burglars who have stolen the
Declaration of Independence! There are clues to be found in the “maze of
streets” representing Washington D.C. and, of course, there is the upper
dimension promised in its title to be traversed with the game’s text parser
interface.

Adventure in the Fifth Dimension