To refill your health, pause the game and press L1, R2, L2, R1, UP, UP, LEFT, SQUARE, RIGHT, CIRCLE, START.

Press TRIANGLE, UP, CIRCLE, RIGHT, DOWN, DOWN, SQUARE, LEFT at the main menu to unlock bonus gallery items. Repeat for more.

To shrink Jamgut, pause and press R2, R2, CIRCLE, R2, L2, L2, LEFT, L2, TRIANGLE.

Save all of the natives to achieve a slightly different ending.

You don't have to kick the Mikkan along the wooden path. Instead, kick it over the first roadblock, turn around and kick it over the gap. After kicking the Mikkan around that part of the path, kick it directly onto the platform just before breaking the glass. However, the stone cliff that your character came in from doesn't have collision detection for Mikkans, so it can get lost if you get too close.