Here is the full list of all 20 Age of Empires: Castle Siege (Windows) achievements worth 200 gamerscore.
Unlocked each civilization's unique troop
Looted 60,000 Stone
Destroyed the Keep 100 times in Multiplayer Battles
Upgraded an Archer Tower to level 5
Looted 100,000 Wood
Built a Stable
Unlocked any 6 heroes
Destroyed 30 Emplacements in Multiplayer Battles
Successfully defended your castle 10 times
Won 3 battles in the Historical Campaign
Unlocked the Catapult from the Siege Workshop
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
Advance to the Eighth Age
Win 2000 Crowns in Multiplayer Battles
Upgrade all civilizations' unique troop to level 4