Here is the full list of all 30 Feral Fury achievements.
Complete Easy Mode
Complete an Entire Stage Without Taking Damage on Normal or Hard Difficulty
Complete Normal Mode
Complete Stage 4 on Hard difficulty
Complete Stage 3 on Normal difficulty
Close 10 Wishing Wells
Unlock 10 Upgrades
Squash 20 lizards
Use 9 Syringe Rooms
Spend 30 Coins on Vending Machines
Send 10 Marines into Battle
Complete Stage 2 on Normal difficulty
Complete Stage 1 on Normal difficulty
Rob a store
Go Through a Teleporter
Complete Stage 5 with a Panda Marine
Complete Stage 5 with Admiral Pawgarr
Complete Stage 5 with Rose the Red
Complete Stage 5 with The Traitor
Defeat The Corrupted with a Panda Marine
Defeat The Corrupted with Admiral Pawgarr
Defeat The Corrupted with Rose the Red
Defeat The Corrupted with The Traitor
Unlock all Secret Doors
Open the Talismans Portal
Return the Missing Book
Get 150 000 points in a Daily Run
Complete Curse Mode
Complete Feral Fighters with at least 9000 points