I could click the music note button on the title screen, but no matter what, the game didn't play any music or sound effects. I had my volume up and could play other audio tracks fine; it was just this demo that was mute.

Hello, Polish translation is gramatically incorrect, game text is missing letters with diacritics (letters like ęóąśłżźćń) and some text is written in Russian, which is a completely different language using cyrillic script. Feels like game text was not human translated and it's sometimes hard to understand what it means....