Here is the full list of all 27 Extinction achievements.
Kill a Ravenii wearing Iron Armor
Kill a Ravenii for the first time
Purchase 1 Upgrade
Kill a Ravenii wearing Thorn Armor
Kill a Ravenii wearing Gold Armor
Kill a Ravenii wearing Bone Armor
Kill a Ravenii wearing Spiked Armor
Complete Campaign
Obtain all possible Stars in Campaign Missions
Complete all Rescue Run Trials
Obtain 3 Stars in all Rescue Run Trials
Complete 5 Skirmishes
Complete 10 Skirmishes
Finish Daily Challenge 5 times
Finish Daily Challenge 10 times
Complete 10 Extinction Battles
Earn a score of at least 1,000,000 in Extinction
Kill 50 Ravenii
Kill 100 Elite Jackals
Kill 1,000 Jackals
Kill a Ravenii while all its limbs are severed
Save 100 Civilians
Save 500 Civilians
Kill a Ravenii with a Spiked helmet
Travel 400 meters without landing
Purchase 15 Upgrades
Purchase all Upgrades