There are 33 achievements worth a total of 1,000 Gamerscore, 6 of which are secret (to reveal the details of the secret achievements, please use this link).
Name
Description
Gamerscore
Castle Crasher
Complete the Legendary Dungeon: Grand Castle
15
Crypt Cleaner
Complete the Legendary Dungeon: Witch Queen Catacombs
15
Did you try turning it off and on again?
Complete the Legendary Dungeon: Ancient Robot
15
Corporate Espionage
Complete the Legendary Dungeon: Secret Corporation
15
Alcazar Shmalcazar
Complete the Legendary Dungeon: Dragon Ruler’s Alcazar