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