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