Weird. I just tried it and it works for me. Clicking anywhere within the boundary of the embedded game window should "activate" the game, then pressing any arrow key starts.
ah I see. I wasn't aware i needed to click one of the arrows. I probably just missed it! Thank you!
No problem! I'll edit the game descrip to make that clearer. I play so many Bitsy games that I'm used to it, but I forget that not everyone is.