The concept of the app is excellent. You have to pass the quests to step to the next levels. It helps you memorize the notes on the fretboard. The app has no problem if you play with your fingers tapping the notes that appear on the mobile phone screen. However, the app doesn’t recognize the sound when you choose to play with your physical guitar even you try to play so loudly. My phone is Xs Max which is too new to cause the problem. So, I bought another app in the same category and it works well with recognizing and detecting the sound from guitar without a time-lag. I hope this issue will be fixed soon and this app will be 5-star rated undoubtedly.