Pet Simulator 99 is filled with hidden locations, mysterious achievements, an unresponsive salesman, and the occasional gift box. One of those locations, or to be more precise, the locked door, is high up in the third area. This massive castle with a huge lock is not something you can unlock this early in the game. As obvious as it may be, in order to get through this door, you have to use a specific type of key.

Once you've unlocked it, you'll gain access to a whole bunch of new features, including the much-needed Trading Plaza from PS99. So without further ado, let's get rid of that padlock.

To open the castle door, you need to use the Castle Key. It is not that difficult to get the key, as you can get it within an hour of playing the game if all methods are used, including Pet Eggs, Golden Pets, Potions and Enchants.

Castle Key becomes part of your inventory when you perform Rebirth 1. To do this rebirth, you need to go to the huge golden statue of Area 25 (Tiki) and use the Rebirth option that appears upon arrival. This will reset everything you have earned so far and lock all previously unlocked areas, but it will not affect your inventory, including pets and items. Additionally, in addition to the Castle Key Teleport, you will also get permanent 75% stronger pets and a gift box.