Rhythm Doctor is a rhythm flash game which only plays with the space button.
Check Rhythm Doctor here : http://www.newgrounds.com/portal/view...
A game by fizzd : https://fizzd.itch.io/rhythm-doctor

This is the tier 6 secret song played perfectly (Rank S). In order to unlock it you need to achieve Rank S on hard version of Tier 3.
Game is still in development, you should support it !