Here is the full list of all 19 Astro Pig achievements.
Regained access to the Ship
Finished all Low-Gravity Zones in the Scrapgarten
Acquired a GGS cartridge
Fiddled around with Make-a-Beat
Acquired the Mechanical Chassis
Regained access to the Ship - again
Acquired the Empathic Crystal
Finished all Low-Gravity Zones in the Nilmines
Finished all Low-Gravity Zones in the Urbs
Acquired the Echoing Relic
Collected all GGS cartridges
Chilled on the ship for 5 minutes
Got a score of 100 or above on Jumper
Got a score of 100 or above on Shooter
Got a score of 100 or above on Looper
Stayed airborne for at least 3 seconds on Jumper
Defeated the Sun Boss on Shooter
Survived for 25 seconds on Looper without collecting anything
Got a score of 175 or above on any GGS minigame