For the 2011 Interactive Fiction Competition, four PR-IF members conspired to create a metapuzzle.

Our four games (entered under pseudonyms) were playable and solvable separately. However, the games had certain elements in common. By observing these elements and considering how they fit together, a player can discover new options in each game — things which are impossible to find by playing the games separately. When these are all discovered, the player can reach a secret ending to the joint game.

Sadly, nobody figured this out during the competition itself. (Although several people remarked on the “coincidental” shared elements.) A few days after IFComp ended, we posted an announcement that there was a metapuzzle spanning the four games. That was all it took; a group on IFMud (notably Carl Muckenhoupt and Michael Martin) worked out the rest within hours.

If you want to try the metapuzzle yourself, play:

If you just want a spoiler tour through the metapuzzle, read this IFMud transcript of the discussion in which players worked it out. (“Hat Mystery” is what they tagged it during the discussion. We’ve happily adopted that name for the metapuzzle.)