Here is the full list of all 54 Hero's Quest achievements.
Defeat the Soul Guardian
Earn 1,000,000,000 Gold
Defeat 500 bosses
Earn 500,000,000 Gold
Reach Level 9,001
Defeat 100 bosses with one hit
Earn 100,000,000 Gold
Play for 10 hours
Defeat the Two Headed Dragon
Earn 20,000,000 Gold
Reach Level 3142
Play for 5 hours
Defeat 100 bosses
Defeat 20 bosses with one hit
Earn 5,000,000 Gold
Defeat the Father Time
Defeat 5 bosses with one hit
Defeat 1 boss with one hit
Earn 1,000,000 Gold
Earn 500,000 Gold
Defeat 20 bosses
Defeat the Void Queen
Reach Level 500
Play for 1 hour
Earn 100,000 Gold
Defeat 5 bosses
Earn 20,000 Gold
Defeat 1 boss
Earn 1,000 Gold
Defeat Yokai
Defeat the Dragon King
Defeat the Jade Dragon
Defeat the Forgetful King
Defeat the Molten Drake
Defeat the Lord Of Chaos
Defeat the Illusion
Defeat 1000 bosses
Defeat 5000 bosses
Earn 5,000,000,000 Gold
Earn 20,000,000,000 Gold
Earn 100,000,000,000 Gold
Earn 500,000,000,000 Gold
Earn 1,000,000,000,000 Gold
Defeat 500 bosses with one hit
Defeat 1000 bosses with one hit
Defeat 5000 bosses with one hit
Play for 20 hours
Play for 50 hours
Play for 100 hours
Reach Level 66,666
Reach Level 100,000
Reach Level 200,000
Reach Level 500,000
Reach Level 1,000,000