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