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