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