Full list of all 41 Monster Sanctuary achievements worth 1,200 gamerscore. It takes around 40-50 hours to unlock all of the achievements in the base game.
The base game contains 34 achievements worth 1,000 Gamerscore, and there is 1 DLC pack containing 7 achievements worth 200 Gamerscore.
Hatch first monster
Complete Old Buran's training
Calm the Blue Caves
Confront the Alchemists in the Library
Defeat the Goblin King
Pass the Oracle's test
Restore balance to the Sun Palace
Recover long lost treasure
Prove a worthy opponent
Explore the forbidden catacombs
Uncover the source of Marduk's powers
Defeat Marduk
Obtain a shifted monster
Evolve a monster
Receive a Tanuki Egg
Obtain all monsters
Win 200 wild encounters
Achieve at least a 25 x Combo
Deal over 10,000 damage in a single hit
Defeat all monsters in a single turn
Five-star a battle
Receive a 5 star score in the Champion Challenge
Receive 5 star scores against all Champions
Discover a hidden room entrance
Enter the Land of Blobs
Uncover the whole map
Help out a resident of the Sanctuary
Upgrade 50 pieces of gear
Complete twenty five battles in the Infinity Arena OR PvP
Beat all of Trainer Gotthelm's challenges
Receive a reward from the Monster Army
Donate 100 Monsters to the Monster Army
Become A Keeper Lancer
Become a Keeper Master
Tread where no Keeper has gone before
Free the Wanderer from their icy prison
Restore the World Tree and learn about the true form of your Spectral Familiar
Fully equip a Bard with instruments
Reach max level with a Monster
Unlock all alternative outfits
Defeat all Legendary Keeper Battles