This author’s great claim to fame in the Apple II world comes from his essential graphic conversion program, SHRConvert / SuperConvert. In its day, it was as essential to the IIGS use as GraphicConverter is today to the Mac user. I can’t possibly write info better about this author that what I found on Byte Cellar: The Vintage Computing Weblog. Written by Blake Patterson, this entry discusses Harper’s Apple IIGS port of the game Airball.
Jason Harper has a web site here.