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