Here is the full list of all 29 Rogue Legacy achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Defeat the asteroids.
Defeat the trademarked chemical.
Defeat all the minibosses.
Defeat the doppleganger.
Find all the runes (purchase not necessary).
Use the special class at least once.
Put at least one point in every skill in the manor.
Beat the game... twice.
Defeat the last boss.
Play the game for at least 20 hours.
Beat one of the clown's games at least once.
Read the last journal entry.
Defeat the boss in the Land of Darkness.
Defeat the boss in the Maya.
Defeat the boss in the Forest Abkhazia.
Defeat the boss in Castle Hamson.
Have one rune equipped in every item slot.
Open your very first gold chest.
Reach level 50 or higher.
Earn your very first Enchantress rune.
Have one piece of equipment in every item slot.
Choose a hero with no traits.
Die 20 times or more.
Kill a chicken.
Find all blueprints (purchase not necessary).
Defeat the brothers.
Defeat the son.
Mock the traitor.
WITHOUT using the Architect, complete the game dying 15 times or less