The tweaked CGA "low-res" video mode that Trixter mentions above is EXTREMELY UNLIKELY to run on video adapters that are not true CGA or compatible (Tandy 16 color video works fine.) In fact, the newer the video adapter, the closer your chance of it running this game approaches zero. :)
One of the few games to use CGA's tweaked "low-res" graphics mode effectively. See screenshots for examples.
"A Note To Programmers" contains the following text:
The code for Round 42 is written in Turbo Pascal. Source code is available from Elven Software Company for a $30 contribution.
Low resolution mode is accessed through a group of Turbo Pascal routines called Lores Toolbox. This package is available from Elven Software Company for a fee of $45. Documentation and demo programs are included with Lores Toolbox.
Functions supported by Lores Toolbox include fast plotting and reading points, plotting circles and lines, writing text, and plotting user defined icons (as seen in Round 42).