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