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