Wow thanks so much for putting this much efford on your feedback i really really aprettiate it, thanks.
About the insync notes you are rigth. I developed a recording system so it was me hitting the keys while listeng to the song, so i may have failed due to fatigue jeje in an up coming update i will fixed that :)
The game do have a song selector it is Just that i have placed it only when you have cleared the game, so if you have winned in easy you will unlocked the song selector in the pause menu for that difficulty, same for medium and hard. ;) It was kind of an easter egg jeje
About the keys i tried many ways to placed it and i find this one rigth in order to have an average level of difficulty but you are rigth. It may not fit everyone so, in an up coming update i will design a key customizer system, so anyone can use the keys they found rigth :D
Everything else, you are rigth, time was not enough to add all those things like combo counter and stuff, but i really would like to take this game to it's full potential, i Will keep working on it and i hope your feedback when that's done :D Thanks so much for taking the time for my game i aprettiate it.