It does have the problem of playability. How do you keep someone's interest beyond a week or two of this?
My thoughts on the subject have lead to something like this:
Create a fairly persistent world. This means that any action a player can make will be permanent in the game. It can be something fairly simple, a grid based game, maybe some resource management. I like the idea of a turn based strategy game, with ~30s per turn.
Create a point system. How points are won doesn't really matter, but make it something interesting. Point reset every week. When they reset, the person with the highest amount of points gets to make a new "rule". This could be anything from a new ability for a unit to a change in the way the physics work. It (obviously) has to be tested and verified, but would be deployed relatively quickly. This process iterates for as long as desired.
Obviously a number of iterations will cause problems of complexity eventually. My thoughts on the matter have led me to a rather specific idea for a game of this type, which I think would be incredibly enjoyable to play.
If you're interested, send me an email. I'd be happy to send you a more complete description of my idea, and if you still like it I'd be up for trying to implement it. That is true for anyone, not just the OP.