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.
In the same issue that the game code was published in, Brian Moriarty makes the game code the test case for cross-comparison between BASIC compilers in the article BASIC Compilers for the Atari:
A Comparative Review. The game program code was actually throttled by requirements for one of the compared compilers:
In desperation, I decided to write this issue’s feature game (Adventure in the 5th Dimension) without using variable GOTOs or GOSUBs, “misplaced” DATA lines or anything else that would violate the restrictions documented by either product.