The controls are listed on the title screen, but they are not listed on the page. I do agree that they could be clearer.
This is an issue with Chrome (and other browsers that don't respect focus on the canvas element), and it is a bug I have noticed in other games that only use the arrow keys. You can play the game in fullscreen, and it won't have this problem. If I were to go back, I would make it WASD for controls.