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 last boss.
Beat one of the clown's games at least once.
Defeat the boss in the Land of Darkness.
Use the special class at least once.
Defeat the boss in the Maya.
Find all the runes (purchase not necessary).
Put at least one point in every skill in the manor.
Defeat all the minibosses.
Defeat the boss in the Forest Abkhazia.
Play the game for at least 20 hours.
Read the last journal entry.
Open your very first gold chest.
Defeat the boss in Castle Hamson.
Have one rune equipped in every item slot.
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.
Find all blueprints (purchase not necessary).
Beat the game... twice.
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