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)
Would be really nice to be able to use this with an acoustic piano.