This is pretty cool! Obviously Decker is not designed for this kind of thing, but that only makes it more cool. :)
I couldn’t get the metronome or the one-voice synthesiser to work, but the tutorial cards and mouse-tracking and even the tone generator worked fine.
As a proof-of-concept, I wasn’t expecting much beyond the addition example on the first card, but you clearly went a lot further than that! Well done!