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