Really liked the art and the music was quite good too. I don't usually play rhythm games (partially because I am really bad at them), but this one was actually really nice!
The boons that you can buy after each successful music were a nice touch.
About the controls. As cool as holding the keyboard as a guitar sounds, sadly, my current setup simply doesn't allow for that (wire too short). WASD works, but is very clunky for a rhythm game since you have to alternate a finger for both W and S. Using F1 through F4 while having the keyboard in its normal position was what I ended up doing, but it meant my hand was pretty far on top of it so I would either let it fall on top of the keyboard (pressing a lot of keys, including Alt, which means I could accidentally do an Alt+F4 the moment I lost focus) or leave it a bit suspended the entire time, which tires the arm quite fast.
My suggestion is quite simple: Either change WASD for something like ASDF or give the player a third set of keys to work with, like UIOP or GHJK. Frankly, the ideal solution is to add custom keybinds so people can change it to suit their needs, but it is a game jam so a third set would do it well enough.
Great game though! I think you have the base for a good rhythm game here!