The game did not work for me under Chrome (it does work on desktop Safari). Is it available in English, or in German only? Thanks!

I think it's also availabe in English. You can switch in the menu, but unfortunately the link doesn't change, so I could not link to the English version and expected it to auto-detect your browser language.

I once played it in desktop Firefox, which worked fine. I'm not on a desktop right now, so can't try. On a phone it's almost unplayable.