Here is the full list of all 38 Pier Solar and the Great Architects achievements.
Defeated the cave guardian.
Helped a hunter in his rabbit hunt.
Won your first battle.
Enriched your knowledge by doing tutorials.
Helped the bounty hunter to retrieve his treasure.
Received all trophies.
Used an ability that requires level 5 gather.
Finished professor Meyer's trials.
Defeated the giant spider.
Defeated the Crab at the sanctuary.
Defeated Ryan the lion.
Defeated the Metal Robot at Timpo factory.
Defeated Ironhart.
Defeated the bakery chef.
Defeated Sasheer.
Defeated the monster living in Teusa.
Defeated the Ludon excavation guardian.
Defeated Kleoneo.
Defeated Cliboe.
Defeated Bethina.
Solve the puzzle in Alina's dream on your first attempt.
Did not give up on hope and fought for a better future.
Gave up on hope and sacrificed yourself for a better future for your friends.
Unlocked the sound test.
Won 100 battles.
Found all spells that can be learned.
Completed Arburus side-quest.
Mastered the slippery game.
Found all master keys.
Found all Sega Genesis cartridges.
Bought all items available in the shops.
Discovered a fragment of another world in yours.
Won 300 battles.
Became a slippery game god.
Collected all the treasures from all chests.
Completed the game fighting only the mandatory battles.
Equipped the best possible items on your characters.
Won 600 battles.