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