Full list of all 54 Overlord achievements worth 1,250 gamerscore. It takes around 40-50 hours to unlock all of the achievements in the base game on Xbox 360.
The base game contains 44 achievements worth 1,000 Gamerscore, and there are 2 DLC packs containing 10 achievements worth 250 Gamerscore.
You won 50 ranked Pillage matches
You won 50 ranked Slaughter matches
You won 10 ranked Slaughter matches
Evil Overlord
You lasted for 30 minutes in Survival
You lasted for 15 minutes in Survival
You lasted for 5 minutes in Survival
You are the True Overlord
Really Evil Overlord
Kahn made you very angry
You have collected all the Tower Objects
You have defeated all Dungeon Creatures
You have an Ultimately Imbued Steel Set
You have an Ultimately Imbued Durium Set
You have harvested a massive amount of Minions
You have an Ultimately Imbued Arcanium Set
You have defeated half the Dungeon Creatures
You have created the Ultimate Horde
You stole Jewel
You have a full Arcanium set
You ground-down Goldo and wrecked Rollie
You have the Arcanium Smelter
You and your Mistress have rocked the Dark Tower
You cured Sir William's disease
You have a full Durium set
You have the Durium Smelter
You put Oberon to Sleep permanently
You have Blue Minions!
You have harvested a huge amount of Minions
You have Green Minions!
You have the Steel Smelter
You have a Mistress
You have Red Minions!
You have harvested a lot of Minions
You punctured Melvin Underbelly
You have recovered the Food
You have started rebuilding the Tower
You have harvested a few Minions
You have retrieved the Tower Heart and powered up the Tower
You won 10 ranked Pillage matches
You won a ranking Pillage match
You completed a ranked Pillage match
You won a ranking Slaughter match
You completed a ranked Slaughter match
You won 25 ranked Expansion Pillage Maps
You won 25 ranked Expansion Slaughter matches
Defeat the Wizard in Legendary Mode
You lasted for 45 mins in a Expansion Survival Map
You've conquered the Ruborian Desert Abyss
You've conquered the Golden Halls Abyss
You've conquered the Evernight Forest Abyss
You have defeated all the Expansion Dungeon Creatures
You've conquered the Heavens Peak Abyss
You've conquered the Mellow Hills Abyss