I sadly can't play in browser, because my arrow keys scroll the page.
Did you try clicking inside the game with your mouse?The browser usually don't forward the input to the game otherwise.
Thank you - that fixes it (though not consistently..). I was trying fullscreen earlier, and the inconsistency + fullscreen not working + arrow keys being on the second layer (fn+IJKL) on my keyboard led me to think it didn't work in general.