Oh, that's weird. What platform are you on? Web version or desktop?
The movement is WASD, not the arrow keys, just in case. I'd be happy to resolve the issue for you
Viewing post in Everything Must Brew jam comments
I would highly recommend the desktop version if you are on Windows or Linux (Linux Mint tested).
Perhaps the cursor was not locked in? There is a small note in description regarding it. If the cursor is visible - press ESC to open the menu -> go full screen mode -> close the menu with your cursor
Let me know if that helps.