Operating System: IBM PC DOS 1.0
How many games has Bill Gates written? At least one, and you’re looking at it: DONKEY.BAS. With the help of Microsoft employee Neil Konzen, Gates coded this whimsical donkey-avoidance game in a late-night BASIC session on an IBM PC prototype. Microsoft included it as a demonstration program for its BASIC that shipped with early versions of PC DOS (the IBM equivalent of MS-DOS, also developed by Microsoft).