Here is the full list of all 28 Distant Star: Revenant Fleet achievements.
Enter the second sector
Level a ship to Regular
Destroy 50 enemy ships
Complete 10 sector nodes
Survive 'The Massacre of Tartarus'
Complete the game on Rookie difficulty
Complete the game on Regular difficulty
Complete the game on Veteran difficulty
Complete the game on Elite difficulty
Enter the sixth sector
Level a ship to Veteran
Level a ship to Elite
Get a full fleet to Elite
Name a Lancer ship 'Wee Stevie'
Destroy 500 enemy ships
Destroy 5000 enemy ships
Complete 'The Broken Soldier' quest chain
Complete 'The Traitor’s Solution' quest chain
Complete 'The Mind of my Enemy' quest chain
Complete 'The Ashes of Home' quest chain
Complete 'The Young Hero' quest chain
Complete 'The Bloodthirsty Spy' quest chain
Complete 100 sector nodes
Complete 1000 sector nodes
Equip 10 attachments
Equip 100 attachments
Equip 1000 attachments
Complete 'The Price of a Life' quest chain