Here is the full list of all 13 Quests Unlimited achievements.
Just began your life as an adventurer.
A potion every now and again can't hurt
Completed 10 quests
You've defeated 10 monsters
You've slain your first boss monster
You've defeated 500 monsters.
You've defeated 5000 monsters!
You've drank 500 potions.
You've drank 5000 potions!
You've defeated 50 bosses.
You've defeated 500 bosses!
You have completed 100 quests.
You have completed 1000 quests!