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