Here is the full list of all 37 Rebel Galaxy achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Join the Mercenaries' Guild
Destroy 1,000 Capital-Class Craft
Find an Antimatter Speck
Purchase a Destroyer-class ship
Purchase a Dreadnaught-class ship
Jump out of the first solar system
Become neutral to pirate factions
Destroy 2,500 Fighter-Class Craft
Reach a Net Worth of 50 Million Credits
Woke Trell
Reach a Net Worth of 5 Million Credits
Break 10 blockades
Rescue 20 merchants
Collect 100 bounties
Complete 50 missions from the mission board
Reach rank 5 in any Guild
Become friendly to the Militia
Find a Progenitor Shard
Purchase a new ship
Join the Merchant's Guild
Hack 10 transponders successfully
Shoot down 500 torpedoes
Gather 200 objects with a tractor beam
Destroy 100 Capital-Class Craft
Salvage 50 Containers
Destroy 250 Fighter-Class Craft
Mine 50 asteroids using a Fault Tracker
Pirate a merchant
Kill 1 Pirate Lord
Successfully bribe a Militia official
Break 1 blockade
Collect 10 bounties
Trade with a Merchant while in flight
Hire a mercenary
Complete the main campaign
Kill 20 Pirate Lords
Find the Face of Gozu