A downloadable game
This was my first game that I ever wrote. I wanted to have a cool response to XYZZY, implementing a room from Adventure; a cool NPC at the top of a mountain; a bear that would follow you; and a simple puzzle where gloves were hidden in scree.
Instead, all the testers couldn't find the gloves, and didn't see any of the game. This completely changed my game philosophy, and led to every single item in my next game, Ether, to be visible, in a single room, with strong guidance.
Play on Gargoyle or Zoom.