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