Here is the full list of all 18 King's Heir: Rise to the Throne achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Finish the final Fight Minigame without using Skip.
Place the crown on Randall's head.
Find half of all Collectibles in the Main Story.
Take a moment for a tankard of liquor.
Feed the animals, big and small.
Take a leap of faith into the water.
Finish a Minigame in less than 30 seconds.
Finish 3 Hidden Object Puzzles without using Hint.
Find the first Collectible.
Finish a Hidden Object Puzzle with less than 3 mistakes.
Finish the first Fight Minigame without using Skip.
Finish a Fight Minigame without making a mistake.
Finish the Lock Picking Minigame without using Skip.
Find all the Collectibles in the Main Story.
Find all the Collectibles in the Bonus Chapter.
Finish a Hidden Object Puzzle in less than 20 seconds.
Finish all the Hidden Object Puzzles without using Hint.
Pet all the animals, even if they run away.