Here is the full list of all 44 Trials of Mana achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Max out magic pot level.
Learn all abilities as any character.
Become a master magician.
Become a master fighter.
Become a master thief.
Open 200 treasure boxes.
Find Li'l Cactus in all possible areas.
Complete Angela's story.
Complete Kevin's story.
Complete Hawkeye's story.
Complete Chapter 6.
Defeat Archdemon.
Complete Chapter 5.
Learn 20 abilities as any character.
Accumulate at least 500,000 lucre.
Open 100 treasure boxes.
Complete Chapter 4.
First ride on Flammie.
Complete Chapter 3.
Accumulate at least 100,000 lucre.
Complete Chapter 2.
First ride on Vuscav.
First class switch.
Complete Chapter 1.
First cannon ride.
Purchase nitromyte for the listed price.
First encounter with Li'l Cactus.
First time learning a chain ability from an unexpected acquaintance.
First time planting a seed.
First time learning an ability.
First time learning a companion's chain ability.
Obtain all achievements.
Stop the end of the world.
Play with all six main characters.
Complete Duran's story.
Complete Charlotte's story.
Complete Riesz's story.
Defeat Anise on hard.
Defeat Mondoragon.
Defeat Dark Lich.
Defeat Black Rabite.
Become a master swordsman.
Become a master cleric.
Become a master guard.