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