[Edit by Eugene:
In a nearby thread Vsotvep noted that there is Play Mode. I thought “Ah, maybe we should publicise this” and moved it to this thread. Actually, I should have left it there and started a new thread, but … done is done, lesson learned… guess what… read on…]
My god, there’s a Play Mode?!
I found a bug immediately: I wanted to play again after my first joseki, but when going back through the move tree, apparently the game itself does not reset (the page does not refresh its url).