A conversation with another A:M-er reminded me of this incident...
About 30 years ago I answered an ad in the Dallas paper from a company looking for someone to do computer graphics.
It wasn't much of a company. It was just a kid in his apartment. I showed him my AMIGA graphics. He said he was making "shareware" games.
"How do you make money if you're giving it away?" I asked.
"The game is free but then they pay for more levels," he said.
He said he'd call me but that was the last I ever heard from... John Carmack.
I couldn't find it in a search, but, I made a PDF the last time I found it...so here is what I have. It's a portion of a thread where all of the controls of muhHair are explained.
Hope that helps.
muhair.pdf