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