Seeing this pains me, because I was working on something similar in 2002, and gave up because I wasn't smart enough to stick with it.

I had a realtime, multiplayer, persistent world, in NES-style 2D (think Zelda 1). Keyboard-based controls, monsters that moved around, etc. All done in cross-browser compatible javascript.

It used a hidden iframe to poll the map data asynchronously (this was way before AJAX) and update the tiles (a 32x32 grid) in real time. I posted it on a popular forum one day, and had a whole bunch of people moving around on the map together. It was so awesome to see my little world come to life. People hadn't seen anything like it.

Then the server admin killed my account. Shared hosting was all I could afford back then.

I kept working on it for a while on my local machine, but without a place to host it, I lost motivation. It really needed a dedicated server, and that was way beyond my just-out-of-highschool budget.

Anyway, I ended up going to college and never really got back to it. 8 years later, I no longer have the source, or even a screenshot.