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