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