Everyone seems to be loving it, but doesn't work for me. I don't control any of the cursors. There's a message in the bottom corner "Area too full, drawing is disabled". Latest Firefox.
Firefox's cursor hiding breaks it, won't let you move the cursor, so don't enable it. Red circled cursor is your actual mouse position, grey circled one is the 'ingame' cursor that's blocked by walls. Move the red onto the grey to start.
The control is hard if you disable the cursor lock, which I had to do to get it to work in Safari. If you lose track of your "game" cursor, you get the red circle around your "real" cursor until you link them back up.
It worked as expected for me in Chrome (then I went back and tried it in Safari after figuring it out).
On Chrome I get "Area too full, drawing is disabled". The site disables my cursor (if I give it permission) and then I simply can't move my cursor, but I can click which creates a ripple around my cursor.