PlayPen is a must-play Indie adventure game which is created constantly by its own players. What does that mean? That means that your adventure can very quickly lead up the nose of a passer by, where you will dig for treasure and eventually become rich beyond your wildest imaginations. Possibly.
The concept is much better described by IndieGames.com, who say: It's a world created entirely by the players and is constantly expanding as users build it up with their weird and wonderful ideas. There's various routes to take and paths to go down, and each leads to more pixelated scenery and ways to venture. Eventually you'll reach a road which has not yet been created, at which point you'll be given the option to draw it yourself and set the next passages. Then other players will be able to continue their story using your scene.