This tidbit was floating around the web around 2003-2005. I have rewritten it, but am not yet ready to include it in the article. No support other than Cadenhead's word.
Rogers Cadenhead, sysop of the Parallax BBS from 1982-86, has claimed the term "door game" was first used on his board. A section of the BBS called the "Zeppelin Door" contained several games Cadenhead programmed. Cadenhead says another sysop cloned his shooting gallery door game and made the source code available, helping to popularize such games.