Here is the full list of all 19 Comit the Astrodian 2 achievements.
Collect 1000 Yellow Stars
Defeat the True Final Boss
Beat the Game
Beat Planet Starlight
Beat Planet Dark
Unlocked Meta Comit
Beat Planet Red
Beat Planet Blizzcicle
Beat Planet Party
Beat Planet Shock
Beat Planet Mechanos
Collect 50 Red Stars
Beat Planet Aquatica
Destroy 100 Enemies
Collect 25 Red Stars
Collect 500 Yellow Stars
Beat Planet Paradise
Collect 5 Red Stars
Collect 100 Yellow Stars