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