King Pig’s Castle is a time limited event where the goal is to pass five levels with a single life.
You can enter King Pig’s Castle in the ‘Fun Stuff’ menu or from the event button on the map screen. You will be taken to a mini-map with five levels. The main objective is to complete those levels without losing a life. If you meet that goal, you can open the treasure chest.
If you quit or fail a level, your progress on the map is erased, and you will need to start over from the first level.