Here is the full list of all 30 Terraria achievements worth 400 gamerscore. It takes around 80-100 hours to unlock all of the achievements on Xbox 360.
The Guide has moved in!
You have completed the tutorial!
You have begun the tutorial!
You have survived the first night!
Get every NPC to move into housing.
Reach the bottom of the World.
Defeat every boss.
Kill every type of slime.
Unlock Hard Mode.
Max out your heatlh and mana.
Corrupt most of the World.
Hallow most of the World.
Defeat The Twins.
Defeat Skeletron Prime.
Defeat The Destroyer.
Travel 42km on the ground.
Remove 10,000 blocks from the World.
Defeat the Goblin Army.
Reach the top of the World.
Wear a full set of vanity clothes.
Find ALL the pets.
Activate 5 buffs at the same time.
Catch some serious air.
Craft 300 items at an anvil!
Smelt 10,000 bars of metal.
Obtain every type of armor.
Place 100 wires.
Survive the Blood Moon.
Use every crafting station.
Travel from the surface to The Underworld and back without dying.