(by request) I made the game QWOP. AMA.
Ask me anything, but I make no guarantees about answering everything.
To answer the first question "why did you make it so hard?": I don't consider it all that hard. I can get halfway to the finish line, which is a hell of a lot further than I can get in Defender, or Pacman, or Pitfall, or just about any other score-based game. Your problem is the framing effect: you expect it to be easy to run 100m. But you probably don't expect it to be easy to clear a score-attack style game!
EDIT: For those who keep asking, the game can be played free at http://www.foddy.net/Athletics.html
EDIT: it seems like new questions have trailed off. Thanks everything for a fun Q&A! Thanks especially to the haters—your tears of rage are like a fine wine to me. And thanks, most of all to everyone who went and bought the iPhone version!!