ICON was one of the very few PC games to use a tweaked 40-column text mode to paint "graphics" with a surprising amount of detail, no doubt inspired by the Commodore 64's "character graphics". It was achieved by changing the character cell height from the normal 8 lines down to only two; the result was an effective resolution of "320x200x16" with the obvious color limitations per character cell.
Check out the screenshots for examples of the advantages (and slight drawbacks) of this unique video mode.
Appears to have been written in Pascal ("Pascal MT+").
Interesting messages found in the game executables and overlays:
Game save file is corrupt - please do not try to edit game files. The file has been deleted for your protection; please start over.
This is an illegal copy of ICON. You should be ashamed of yourself!