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