Tak and the Power of Juju Cheats

Pause the game

After you go to the Burial Ground you should see a cage. You will also
see a sign that says DO NOT OPEN CAGE. The only way to get to Chicken
Island is to open the cage.  You should see a tree with one of those
monkeys in it. You should see one of those plants that give you melons.
Back up and throw a melon at the Monkey. If you are backed up far enough
the should throw the melon at the cage. Inside will be a rhino. Break
the fence in front of you and you are on your way.

Collect all 12 Plants to unlock the "Concept Art" option at the extras menu.

During the game hit: left,right,square,square,O,O,left,right.

Now go to the extras menu to activate the cheat.

Get All Yorbells:
During the game hit up,triangle,left,square,right,O,down,up.

Now go to the extras menu to activate the cheat.
If you collect all 200 yorbells, you can view the storyboard.

Collect all twelve plants to unlock the Concept Art, which can be found in the Extras menu.