I put together the first draft of a puzzlehunt. Then I let some people playtest it. And they had much better ideas for the puzzles. So I used those. Then I let a bunch of people play the resulting game.
You can still play it: The 2-Tone Game.
These are some notes about the game. If you hope to run something similar one day, they might help you. As long as you avoid the notes about particular puzzles, you should dodge spoilers OK. Oh, except the source code is full of spoil in a couple of places, too.
A lot of this stuff is just kinda random non-spoilery essays.
There's a lot of rambling here, but maybe not about the topic you were hoping for. Your questions and comments are welcome.
The 2-Tone Game started out as a computer programming project. This should not surprise you; I'm a computer programmer. I wanted to write a puzzle hunt hint/answer confirmation system.
I've seen many hint/answer confirmation systems. Probably the one that impressed me most was Shinteki's "LEON", an application that ran on hand-held Palm devices. Shinteki runs some of the best games out there; and LEON is part of what makes them so good. Then again, they're willing to deal with the logistics of keeping track of those Palms—getting them to players, getting them back.
I'd volunteered at a couple of MicroSoft puzzlehunts. Their hint/answer confirmation system is an internet server. If there's a central server that all the players interact with, that lets you do some nice things as GC—keep track of all the players, say "we'll unlock this puzzle if three people have solved that one," that kind of thing. Players need a network connection to talk to the server. But that's OK; those games take place in conference rooms at MicroSoft.
So I started designing a hint system. It was a pretty vague design. I wasn't sure what kind of game I was writing it for, and was falling into frameworkitis, a system that was designed to be soooo general that it worked poorly in any situation.
So I wrote a little game to go with it, and the game and the software grew up together. And here we are.
2015 update: Then, in 2015, the auth system the hint system was based on largely went away: Google stopped supporting OpenID 2.0.