Here is the full list of all 60 Legend of Grimrock 2 achievements.
Enter the Castle
Collect four elemental essences
Enter the Crystal Mines
Defeat the Ratling Boss
Defeat the Wormbound brothers
Perform 500 missile or throwing weapon attacks
Find Bane
Open the gate to the Cemetery
Dig up three treasure chests
Kill 250 monsters
Defeat a monster with a backstab attack
Cast 500 spells
Open the door to the Archives
Find 25 secrets
Max out a skill
Kill a monster by teleporting on it
Mix a total of 50 potions
Travel 10000 tiles
Cast 250 Spells
Dive 250 tiles
Defeat Herder's Den
Kill a monster with a single blow
Find 10 secrets
Visit 10 levels
Mix a total of 10 potions
Collect an elemental essence
Perform 500 melee weapon attacks
Cast 25 spells
Defeat the Viper Roots
Deal a killing blow with unarmed attack
Enter the Nexus
Complete the game with hard difficulty setting
Complete the game with old school mode
Perform 100 power attacks
Learn 15 spells
Polymorph 10 times
Find 50 secrets
Find all secrets
Dig up all treasure chests
Find 8 skulls
Find the pie
Assemble the Meteor Hammer
Catch 25 fish
Open 5 gold locks
Max out three skills
Visit all levels
Collect and wear archmage's uniform (4 pieces)
Collect and wear rogue's wardrobe (5 pieces)
Collect and wear full set of Crystal armor (6 pieces)
Collect and wear full set of Meteor armor (6 pieces)
Defeat the Summon Stones
Defeat the Lindworm
Enter the Shrine of Balance
Enter the Pyramid of Umas
Summon the Viper Roots in under 6 minutes
Kill a monster by throwing pants at it
Reach level 10 with a farmer
Defeat a Magma Golem
Find the Relic
Complete the game with Ironman and Single-use Crystals modes turned on