It's Miraculous DJ: Felix Style! After Plagg messed with it. This was his way to get back at Felix for smushing his cheese under Adrien's pillow. All you have to do is press space to start the music, then press the number and letter keys however you want to make a song!
This is from @OrigamiPig who make the original, better one. Check that out. The music backwarder is pretty cool though.
