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