Here is the full list of all 15 Flooded achievements.
Finish the first level of the Campaign
Destroy the Pirate Gunship
Destroy the Pirate Base
Destroy the Machine
Lose the first level of the Campaign
Win a game in Quick Game mode
Win 5 games in Quick Game mode
Win 10 games in Quick Game mode
Unlock all Relics
Win a game with each Commander
Survive until the second cycle in Endless mode
Survive until the third cycle in Endless mode
Survive until the fifth cycle in Endless mode
Develop 20 technologies to maximum level
Achieve a building performance of 6