Thank you so much for your kind words and detailed, helpful, & constructive feedback! Agree with both points - we want to add some variety to the sound effects and make them a little less frequent. Also would have loved to pause the background music when the track sound played. Those are both on our backlog.
We are considering expanding the game to include a battle mechanic when the player enters the ethereal realm, and a meta-layer progression system where the player can upgrade offensive and defensive equipment & skills. Can't wait to share more!