This was awesome! I would love to play a fleshed out version of this especially with different genres and more abilities. At first I was a little confused because I thought any note within a key that was not yet established were all valid; I think a rule about how cards should be in an ascending scale would have helped me! Appropriate cards being highlighted was a good tip that got me out of that trap though, so I'm grateful for that.
Special shoutout to the the level of detail in the music! Loved the layering of instruments with each card, how songs are in the same key, and the crescendo when you complete the scale. Certain to tickle musician gamers :D Well done!