Here is the full list of all 12 Defenders of Ardania achievements worth 200 gamerscore.
Build all tower types of one race in one mission.
Survive 60 waves on the Survival game mode.
Sell 10 towers in a single mission.
Destroy the Minotaur Base.
Win a level without towers.
Use the unit info 10 times.
Finish the first mission.
Finish the Campaign.
Use all Economy Upgrades in one mission.
Win 5 multiplayer match in a row.
Complete all levels in Limited Resource mode.
Unlock all achievements.