The problem is the world is too big. If you could get a rough fix on where your user is and start with a focus on their local area you might get some engagement. Allow just how big it is to be something they might discover.
Looks like wplace.live. But you can get 256 pixels an hour, instead of 60 and ownership of tiles is permanent. Cool idea. Do you really expect a lot of people to pay for tiles?
This would be cool if it was free and everyone could just draw.. There are plenty sites like that atm tho.