It's a very cool little game! One suggestion: could you make it so you can noodle around on the keyboard without submitting the answer and then once you've worked it out, have a submission mode? Right now, it's frustrating that if you enter a wrong note, it shows a message, so you can't experiment on the keyboard to try to work it out.

Thanks everyone for the feedback! I've added a bunch of new updates, just thought I would consolidate to this message since its pinned near the top.

*Changes*

- Ableton keyboard layout for ladidahh also thanks for a user name that I had to type about four times because of my phone's autocorrect! :)

- Tempo sliders for practice and Simon modes

- Lock icon which lets you freeze the difficulty at a certain number of notes in Practice mode instead of constantly increasing

- Floating display window in settings which displays stave and note that you are currently playing on a midi keyboard.

*Future Updates*

- Noodle time (let you play around to experiment before going O'Reilly Live)

- Markov or Transformer (thanks viraptor) approach to generate more sonically pleasing melodies

- Pianistic echoes (caetris24) - an optional visualization for the onscreen keyboard almost like a heat map pattern

- Fix the weird iPhone audio issue (EdNutting had some good advice on this)

- still looking at adding the Tracker 4-layout as proposed by moosedev

*Helpful fixes*

- Some midi controllers don't send a corresponding NOTE_OFF, instead they send a NOTE_ON with velocity of 0 (Thanks ta2112 for this helpful info)

That's a good idea - I'll try to get that implemented this evening.

You read my mind sir! Also, great work by OP, I really needed this since a long time!

came here to write this comment, +1!