Unlock Hidden Atari Clasic
At the main title screne, press and hold Select + R2 on controllers 1 & 2. This should unlock the "Two Player Vs" option.
Level Select
Hold Left + L2 and press select on the main menu. If entered correctly, a sound should play
Secret Levels
Complete every mission. At mission select, go to the lowest mission and repeatly press Down + Right until a new mission, Operation Power-up, appears.
For the following codes, Pause the game and enter:
Cycle through gun modes: Select, L2, Select, R2, Select, Select, Select.
Fly Through Buildings: Select, L2, Select, R2, Square, Square, Square, Square.
Invincibility: Select, L2, Select, R2, Triangle, Triangle, Triangle, Square.
Level Skip : Select, L2, Select, R2, Triangle, Triangle, Triangle, Down, Down, Down.
Maximum Fuel and Armor: Select, L2, Select, R2, Triangle, Triangle, Triangle, Circle.
Maximum Weapons: Select, L2, Select, R2, L1, L2, R1, R2.
Perfect Pause : Select, L2, Select, R2, Down, R1, R2.
Summon Wingman: Select, L2, Select, R2, Square, Square, Square, Circle.
Upgrade Current Weapon : Select, L2, Select, R2, L1, L1, R1, R1.