Clean and responsive UI, the game is easy to pick up and understand (be careful about not giving too much information through text though).
Having a save and load system is also neat, since you're aiming for a casual type of game to play from time to time.
What the game lacks most is pacing, as I spent more time waiting than actually playing. maybe you could add a button to speed up the game to overcome that (like a 1x, 2x, 4x, 8x game speed).
Also cool music, love the guitar.