Level Select:
At the main menu press UP, LEFT, CIRCLE, CIRCLE, LEFT, LEFT, SQUARE, DOWN, UP, CIRCLE 

Level Skip:
During gameplay press SQUARE, TRIANGLE, LEFT, DOWN, RIGHT, TRIANGLE, RIGHT, UP, X 

Invincibility:
During gameplay press X, TRIANGLE, RIGHT, LEFT, CIRCLE, UP, DOWN, DOWN, RIGHT, CIRCLE, CIRCLE 

Extra Damage:
During gameplay press X, TRIANGLE, RIGHT, UP, RIGHT, TRIANGLE, CIRCLE, RIGHT 

Burn Everything:
During gameplay press SQUARE, TRIANGLE, LEFT, DOWN, SQUARE, CIRCLE 

Goat Mode:
During gameplay press TRIANGLE, RIGHT, LEFT, LEFT, CIRCLE, TRIANGLE, SQUARE, RIGHT, UP