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