Hmm.. the only disadvantage to this game is that people would need cameras or scanners. Plus the limit was on pen which I assume are uncomfortable to people who are not committed to finalizing parts of the drawings. I suggest you make it broad in medium letting others with digital and pencil skills to join. no one can beat my stickman drawing of Silk! (^@_@)^
The idea is not to produce a masterpiece. Being limited with a single tool (pen), people are bound to make mistakes. The point is to show how it goes despite that. Besides, what's a challenge for if we stick to what we're comfortable in right?
I agree with the camera/ scanner thing though.
This goes to all my friends, new, old and the ones
I've lost over the years but have never forgotten.