Here is the full list of all 11 Neversong achievements.
Beat the entire game without getting hit!
Beat the entire game in under 1 hour!
Beat the entire game without dying!
Beat the game twice!
Collect all Coma Cards!
Cheat by playing songs out of order.
Enter all the secret rooms with the Gemstone Key!
Beat Dr. Smile in less than 5 minutes!
Beat Skunky's Granny in less than 5 minutes!
Beat Jon's Dad in less than 5 minutes!
Beat Simeon's Mother in less than 5 minutes!