The VELVET Add-on for Groove Coaster has 6 achievements.
Play VELVET 20 times
Play VELVET and clear all of SIMPLE, NORMAL and HARD
Play VELVET and get A Rank in SIMPLE, NORMAL and HARD
Play VELVET and get S Rank in SIMPLE, NORMAL and HARD
Play VELVET and get S+ Rank in SIMPLE, NORMAL and HARD
Play VELVET and get S++ Rank in SIMPLE, NORMAL and HARD