It would be nice if the "how to play" screen gave keyboard equivalents. I was about to give up trying to play until I saw someone's comment about arrow keys.
This is tricky on laptops with touchscreens and keyboards, and iPads with keyboards. Seems there’s no good way to ask “is there a keyboard attached” or “what is the primary input method.” So I have to pick one set of instructions to show based on a guess, even though both inputs are acceptable.
For me (Firefox, Linux) it did give keyboard instructions on the how to play screen.