Here is the full list of all 20 Age of Empires: Castle Siege (UWP) achievements worth 1,000 gamerscore.
Won 3 battles in the Historical Campaign
Won 100 Crowns in Multiplayer Battles
Advanced to the Eighth Age
Won 20 Multiplayer Battles
Unlocked each civilization's unique troop
Destroyed 30 Emplacements in Multiplayer Battles
Unlocked any 6 heroes
Looted 60,000 Stone
Destroyed 40 Walls in Multiplayer Battles
Looted 100,000 Wood
Successfully defended your castle 10 times
Looted 30,000 Food
Built a Stable
Upgraded an Archer Tower to level 5
Unlocked the Catapult from the Siege Workshop
Unlocked the Ladder Invaders from the Barracks
Advanced to the Second Age
Destroy the Keep 100 times in Multiplayer Battles
Win 2000 Crowns in Multiplayer Battles
Fully upgrade each civilization's unique troop