Here is the full list of all 20 Age of Empires: Castle Siege achievements worth 200 gamerscore.
Fully upgraded each civilization's unique troop
Advanced to the Eighth Age
Won 2000 Crowns in Multiplayer Battles
Unlocked each civilization's unique troop
Looted 60,000 Stone
Upgraded an Archer Tower to level 5
Built a Stable
Successfully defended your castle 10 times
Destroyed the Keep 100 times in Multiplayer Battles
Looted 100,000 Wood
Unlocked any 6 heroes
Destroyed 30 Emplacements in Multiplayer Battles
Unlocked the Catapult from the Siege Workshop
Won 3 battles in the Historical Campaign
Looted 30,000 Food
Destroyed 40 Walls in Multiplayer Battles
Won 100 Crowns in Multiplayer Battles
Won 20 Multiplayer Battles
Unlocked the Raiders from the Barracks
Advanced to the Second Age