The holy grail of game design - a game driven by nothing but an on/off state - is a very interesting field of study. Everyone should make one.

http://www.gamasutra.com/features/200506...n_01.shtml

NS-Tower is probably my favorite single-button game. A lot of people like that one snake/cavern game (re-hashed in the uDG entry SolarQuest with some elaborations.) You can take a game and put everything except one button on auto-pilot- Warioware has a lot of stripped-down microgames like that.

How about a text adventure using morse code

I loved this article. I think I'm going to be using purely mouse input for my 21 Days entry, which is as close to one-button as you can get (like they're describing, anyway). They have a track ball in the game to control some stuff, I believe.

A track ball would work perfect for my 21 days entry...