Full list of all 78 For The King achievements. It takes around 80-100 hours to unlock all of the achievements in the base game on Windows.
The base game contains 72 achievements, and there is 1 DLC pack containing 6 achievements.
Clear the Flooded Crypt
Escape the Mage Dungeon
Defeat Vexor on Apprentice
Reach the top of Harazuel
Fly in the Air Balloon
Purge the Buried Temple
Clear both Demon Caves
Unlock the armory
Kill 5 Snowmen
Defeat the Yeti, free her "prisoner"
Defeat the Sea King
Crush 25 Imps
Clear 5 Sea Caves in 1 game
Defeat the Songstress
Honor 50 Stone Heros
Unlock 40 items from the Lore Store
Survive the Lava Dungeon
Defeat 100 Beastmen
Kill the Kraken
Defeat 10 Mimics
Complete 50 Side Quests
Smash 150 Skellys
Defeat the Royal Droll
Kill 1000 Enemies
Defeat the Old One
Topple 15 Crag Monsters
First party wipe
Have 1500 Gold
Murder 30 Hags
Unlock 20 items from the Lore Store
Kill 30 Fishfolk
Find Bradach's Cabin
Solve the King's Maze
Clear the Forgotten Cellar
Defeat the Mind Bender
Defeat Deimos
Defeat the Hangman
Honor 15 Stone Heros
Defeat the Foul Priestess
Break a sieged town
Defeat 3 Triclops
Use 100 herbs
Help Hildebrant retrace his steps
Reach the Inferno
Use 10 candies
Kill 10 enemies with Firearms
Reach the bottom of Hildebrant's Cellar
Defeat Disciple
Enter Hildebrant's Cellar
Defeat Lucky
Break a weapon
Honor 3 Stone Heros
Unlock 1 item from the Lore Store
Defeat the Lich's Crypt
Have 300 Gold
Revive a party member
Defeat Coal Heart
Purge the Glittering Mines
Defeat the Bandit King
Complete 1 Side Quest
Defeat the Cultist Camp
Clear a Cave
Kill a thief attempting to flee
Defeat Vexor on Journeyman
Defeat Vexor on Master
Defeat the Chaos Beast
Have 5000 Gold
Slay the dragon at the top of Frostbite Peak
Win a game of Gold Rush
Purge all 4 Water Temples
Find Captain Greenbeard's Ship
Get killed by a suicidal enemy