Ok, so this post will be more substantial than the last:
New link, same game. . . Or is it? Well, aside from the change in the maze, it's actually the same game. But in 3D!
The light/dark in the last game is essentially a camera, and it is used to detect how far walls are from the person. Add some clipping and scaling, and it makes a Doom-like First Person view.
I bolted on the MMO stuff I had made from the, well, MMO I was working on. This gave it the multiplayer.
How it works.
It uses a method called "ray casting" which basically renders the screen into vertical stripes and computes how far away these stripes should be. A distant wall is a small stripe, and close one fills the whole screen. To get images to work, they are cut up into lots of small pieces, and then scaled in the same way walls are.
There are some limitations, the maze is flat (no stairs or things like that), because it's exactly the same game as posted in my last blog. It's just a top-down game, rendered into a fake sense of 3D.