Here is the full list of all 9 Drums Rock achievements.
Unlock the 2nd act.
Complete a song in Medium difficulty for the first time.
Get 8 Stars.
Complete a song in Easy difficulty for the first time.
Complete the Game Tutorial for the first time.
Get 130 Stars.
Complete a song in Hard difficulty for the first time.
Complete the Campaign Mode.
Unlock the 3rd act.