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.
Play as Frog.
Reach Level Ultra as Skeleton.
Unlock all Crowns as one character.
Loop as every character.
Reach 2-1 on Hard Mode as Chicken.
Reach the Nuclear Throne in under 10 minutes as Plant.
Defeat Captain.
Defeat Captain as Rogue.
Defeat Hyper Crystal as Horror.
Defeat Mom as Rebel.
Unlock Hard Mode.
Defeat the Technomancer as Steroids.
Defeat the Technomancer.
Unlock a Golden Weapon for every character.
Sit on the Nuclear Throne as headless Chicken.
Defeat Hyper Crystal.
Reach the Nuclear Throne with Melting without choosing Rhino Skin or Strong Spirit.
Eat a Hyper Weapon as Robot.
Reach 7-3 on a Daily.
We hereby sincerely apologize.
Defeat Mom.
Reach Level Ultra as any character.
Loop past the Nuclear Throne.
Defeat Throne II.
Loop the game.
Reach 4-? as Crystal.
Reach 2-? as Eyes.
Reach the Nuclear Throne.
Unlock a Crown as any character.
Defeat the Nuclear Throne.
Reach 6-1.
Defeat Lil Hunter.
Reach 5-?.
Unlock a Golden Weapon as any character.
Reach 3-?.
Defeat Horror.
Reach 5-1.
Die.
Defeat Big Dog.
Reach 3-1.
Reach 2-1.
Defeat Big Bandit.