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