Here is the full list of all 60 The Quest achievements.
Break out of jail
Pickpocket successfully 50 times
Complete Kill the Witch Queen quest
Attain 40 base Dexterity
Attain the outfit rank 'Fashionable'
Kill the Cyclops King
Complete 45 quests
Cast 250 spells
Read 12 non-magical books
Mix 100 potions
Perform 2000 ranged attacks
Find the treasure island
Complete 25 quests
Attain 40 base Strength
Amass 100000 gold
Complete Nobleman's inheritance quest
Repair 100 items
Perform 500 ranged attacks
Mix 25 potions
Perform 2000 melee attacks
Find the Sunken Monastery
Kill 250 monsters
Travel 20000 tiles
Cast 50 spells
Complete 10 quests
Perform 100 ranged attacks
Find the Abandoned Mine
Kill 100 monsters
Perform 500 melee attacks
Enjoy the services of Madame Rosalia's House of Fleshy Delights
Complete Matras infection quest
Kill 25 monsters
Perform 100 melee attacks
Get thrown into jail
Cast 1000 spells
Mix 250 potions
Attain 40 base Endurance
Attain 40 base Intelligence
Attain 40 base Personality
Attain maximum positive fame
Attain maximum negative fame
Reach the good ending
Reach the evil ending
Win 100 card games
Complete Join the Thieves' guild quest
Learn all Undead spells
Drain 1000 health by using spells
Learn all Attack Magic spells
Travel with the Sea Captain in every port
Meet one of the makers of The Quest in game
Kill 10 Firebirds
Complete Bring Eckinish to Dagma quest
Find a use for all Idols on Thule and Eldfell
Kill The Beast
Find the lost spring
Complete Bribe the sea captain Moruu quest
Kill 20 Flesh Eaters
Reach the good ending of Islands of Ice and Fire
Reach the evil ending of Islands of Ice and Fire