Here is the full list of all 76 Iron Marines achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Find the 6 Immensity Stones to awake the awesome Mitten of Tranos.
Recruit a total of 41 fighters in the Ga’r Warhalls.
Win Spec Op 'The Last of Them' in less than 7 minutes.
Beat the Spec Op 'The Colour out of Space' having destroyed all Bishop cocoons in the process.
Defeat 50 tentacles in Mission 13.
Help the broken Protocol Droid on Mission 10.
Have at least 4 Brawlers active at the same time in Mission 8.
Teleport all colonists to safety in Spec Op Darkest Hour.
Complete Mission 7 without losing any Squads.
Destroy 8 Worm Cannons in a single Mission.
Have the worm throw 5 Holy Hand grenades at the enemies' faces.
Have 4 Ranger Squads fighting at the same time in a single Mission.
Complete all Campaign Missions in Impossible difficulty.
Defeat Nexus, the Raad Vanguard Master, in Impossible difficulty.
Destroy 30 Raad Portals before any enemy can enter our galaxy through any of them.
Help the squad of funny penguins achieve maximum coolness on stage 15.
Defeat Mr: Rob070 in Impossible difficulty.
Help the Doctor travel through the timey wimey stuff in Mission 11.
Make the Compactors kill 50 Peripheroids.
Defeat the Fell Tyrant in Impossible difficulty.
Destroy the Fell Bishop's cocoon in less than 4 minutes.
Save all base colonists in MIssion 5.
Search for the ultimate answer buying 42 different upgrades.
Defeat Nexus, the Raad Vanguard Master, in Normal or Veteran difficulty.
Kill 50 Alpha Fenrirs during a single try of stage 18.
Destroy a total of 72 Ice Blocks.
Find the 4 mischievous kids lost in the snow on stage 19.
Help the frozen, weird-looking alien squirrel get his preferred food on stage 18.
Have 3 Heroes reach maximum level.
Destroy a total of 46 Raad Carriers.
Complete a Mission with at least one Brawler, one Shellstorm and one Firewalker at the same time.
Kill a total of 150 Jackbots resurrected by Oculus.
Defeat Mr: Rob070 in Normal or Veteran difficulty.
Build a total of 149 Towers.
Have a Hero reach max level.
Deploy 77 Empyrean squads onto the battlefield.
Deploy any Hero to battle 100 times.
Spend 10000 Credits at the Arsenal.
Complete Spec Op Laser Tag with the prototype Dropgun unharmed.
Have 100 of your Squads die. They will be missed.
Help Sandro unlocks his cowabungous inner self.
Kill a Spammer before it spawns any Inductors.
Free the cute alien from The Claw's grasp in MIssion 12.
Capture all 3 Core Processor's switches without ever losing any of them in Mission 11.
Kill 20 or more enemies in less than 3 secs.
Destroy the same Assembly Center 3 times.
Kill 343 Peripheroids.
Complete Mission 9 without losing a single Squad, like a miniature giant space hamster could do.
Earn a total of 5000 Credits.
Defeat the Fell Tyrant in Normal or Veteran difficulty.
Kill 7000 enemies.
Defeat the Fell Bishop in the Spec Op A New Despair in less than 30 seconds.
Beat Spec Op Into Darkness with all survivors.
Attack 1000 times with Rocket Towers.
Teleport the five missing Captains scattered in Sagan-1.
Earn more than 5000 Techpoints.
Complete the Spec Op In Brightest Day with both Power Cores active.
Save the Ambassadress, save the world!
Wake 21 Grimcrushers from their stone slumber.
Extract 10000 Etherwatts.
Kill 4000 enemies.
Rain down a total of 100 Dropguns to the battlefield.
Target to shoot 9 alien jellyfish until they explode.
Kill 17 Etherleeches before they drain your Etherwatts storage.
Kill a total of 300 enemies in Emergency Frequency Spec Op.
Complete Mission 4 only deploying Mechas.
Spend more than 1987 Etherwatts in a single Mission.
Destroy 11 Fell Refineries.
Help the space monkeys get the secrets of the Monolith in Mission 4.
Extract 1000 Etherwatts.
Kill 500 enemies.
Rescue all 4 wounded soldiers in Mission 3.
Buy any Upgrade from our wonderful selection.
Complete Mission 2 with the COMSAT taking no damage at all.
Complete Mission 1. We knew you could do it.
Click their portrait repeatedly to annoy a Hero during a Mission. They like it!