Your instructions initially say to use WASD to move, which is inconvenient for those of us with our pointing device on the left. But it turns out the arrow keys work as well, and the in-site instructions say so (when you manage to click the instructions button, which is quite hard with a trapped pointer).
This was Chrome on Linux. I had a crosshair cursor in the centre of the screen, and the mouse was just doing looking, so I had to look in a direction that made the button move under the cursor (or something like that - I'm now elsewhere so can't check).
