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