PlayPen is a world. In fact it's your world - and I mean that inclusively. I guess I should say that it's everyone's world, because it belongs to everyone. Everyone in the world. Let me explain.
As you wander through the world of PlayPen, clicking from picture to picture by depressing your left mouse button whenever you find an interesting text prompt hidden in the images, you visit places, people, ideas and imaginings created by other players. Sometimes a text prompt will include the words (Draw new page). If you follow one of these prompts, you'll find yourself looking at an empty image and a simple set of drawing tools. This is your opportunity to get creative. Please try to remember how you got there though, so your new page makes sense when other people come to visit it. Also, if you're looking at someone else's page and you think I have a great idea that would make this page even better, please hit the Draw Here button and edit that page. Oh, and don't worry about making mistakes. PlayPen is built on top of MediaWiki (the technology that runs Wikipedia) so it keeps a full edit history, which means you can roll back to previous versions of each and every page.
PS: PlayPen may contain content inappropriate for the workplace or children. Parts of it are also rather childish.
During initial development PlayPen received a heap of great feedback and support from its testers, all of whom are fantastic game developers. You can still find their PlayPen contributions branching off the Main Page Memorial Park! In particular I would like to thank benzido (who not only named the project but also runs a tumblr of the best pages), increpare, Zaphos, Jonathan Whiting, Superflat, and Rob Fearon.