Here is the full list of all 9 Once Upon a Jester achievements.
Unlock all stickers.
Find the fish.
Play the right tune for all Callers during Jerry Jeremy’s radio show performance.
Find Pesto.
Steal the Royal Diamond.
Pop the frog into popcorn over the campfire.
Make the perfect smikkel.
Finish the game!
Watch Freek get pulled into the sea by the kraken.