Tips and Tricks
Groove Coaster can be easier to play if you hold your iPhone the other way up (on it's side).
Unlock The Beginning Stage
After completing the first set of songs, you unlock 'The Beginning' track. This scales in length depending on how far you are through the game, so is worth revisiting frequently.
Unlock Medium/Hard Songs
To unlock the Medium and Hard versions of each song, simply complete the song on Easy difficulty.