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.
Defeat the boss in the Land of Darkness.
Defeat the boss in the Forest Abkhazia.
Kill a chicken.
Play the game for at least 20 hours.
Defeat the boss in Castle Hamson.
Open your very first gold chest.
Choose a hero with no traits.
Reach level 50 or higher.
Have one rune equipped in every item slot.
Have one piece of equipment in every item slot.
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).
Defeat the boss in the Maya.
Defeat the last boss.
Defeat all the minibosses.
Beat the game... twice.
Read the last journal entry.
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