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.
Find all blueprints (purchase not necessary).
Beat the game... twice.
Defeat all the minibosses.
Defeat the last boss.
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.
Read the last journal entry.
Defeat the boss in the Land of Darkness.
Defeat the boss in the Maya.
Play the game for at least 20 hours.
Defeat the boss in the Forest Abkhazia.
Beat one of the clown's games at least once.
Have one rune equipped in every item slot.
Defeat the boss in Castle Hamson.
Open your very first gold chest.
Reach level 50 or higher.
Have one piece of equipment in every item slot.
Earn your very first Enchantress rune.
Kill a chicken.
Die 20 times or more.
Choose a hero with no traits.
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