Here is the full list of all 44 Nuclear Throne achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Unlock all Crowns as one character.
Loop as every character.
We hereby sincerely apologize.
Reach Level Ultra as Skeleton.
Unlock a Golden Disc Gun or Golden Nuke Launcher.
Defeat Captain as Rogue.
Defeat Hyper Crystal as Horror.
Defeat Mom as Rebel.
Sit on the Nuclear Throne as headless Chicken.
Reach 2-1 on Hard Mode as Chicken.
Eat a Hyper Weapon as Robot.
Defeat the Technomancer as Steroids.
Reach the Nuclear Throne with Melting without choosing Rhino Skin or Strong Spirit.
Play as Frog.
Reach the Nuclear Throne in under 10 minutes as Plant.
Unlock a Golden Weapon for every character.
Reach 7-3 on a Daily.
Defeat Captain.
Unlock Hard Mode.
Defeat the Technomancer.
Defeat Hyper Crystal.
Defeat Mom.
Loop past the Nuclear Throne.
Defeat Throne II.
Loop the game.
Reach 4-? as Crystal.
Reach Level Ultra as any character.
Reach the Nuclear Throne.
Unlock a Crown as any character.
Defeat the Nuclear Throne.
Reach 2-? as Eyes.
Reach 6-1.
Defeat Lil Hunter.
Die.
Reach 2-1.
Reach 3-1.
Reach 3-?.
Reach 5-1.
Reach 5-?.
Defeat Horror.
Unlock a Golden Weapon as any character.
Defeat Big Bandit.
Defeat Big Dog.
Get 100% of the unlocks.