Press UP(2), DOWN(2), LEFT, RIGHT, LEFT, RIGHT, CIRCLE, X, CIRCLE, X during the level 1 loading screen (and before it ends). The background music will change to a remix of the first level of Contra.
Press UP(2), DOWN(2), LEFT, RIGHT, LEFT, RIGHT, CIRCLE, X, CIRCLE, X during game play in multi-player mode after you lose your final life while your partner is still alive. You will resume with one last life in Arcade mode or two more lives in Rising mode.
Uprising R (30 lives) in Customization shop:
Press UP(2), DOWN(2), LEFT, RIGHT, LEFT, RIGHT, L3, R3 at the "Press Start" screen.
Game completion bonus:
Complete the game to unlock the ability to purchase 30 lives at the upgrade shop for 53 million CP.
Level 2: Unlimited CP:
To gain unlimited CP in level 2, get a plasma gun (H) and save it until the second mini-Boss. Go to the right side, charge the plasma gun, then crouch and kill all of the alligators. While doing this, shoot the gun horizontally at all bombs that the helicopter drops to increase your combo. Fire vertically when a bomb falls overhead. Do not shoot the helicopter. You can build a 60 combo and get about 50 million CP before the combo meter stops. When you start earning negative points, intentionally die. Restart the level and repeat as desired.
Purchase 30 lives:
Complete the game to unlock the option to buy 30 lives in the upgrade shop for 53,000,000 CP.
Let's do this thing right! - Arcade mode: Defeat 10 or more Privates.
Stage Clear - Arcade mode: Clear Stage 1.
All Clear - Rising mode: Clear all missions.
Decorated Soldier - Rising mode: Obtain all medals.
Burning Spirit - Rising mode: Achieve the highest rating on all stages.
You can never play too much. - Rising mode: Purchase all obtainable items.
The Strongest Warrior - Arcade mode: Clear all missions.
Innate Guerilla Warfare - Arcade mode: Clear all missions without defeating more than 50 Privates..
Disposable Warrior - Arcade mode: Stock up 20 or more extra lives.
World Peace - Arcade mode: Clear all missions with friends from around the world.
The definition of a warrior! - Arcade mode: Clear all missions without picking up any weapon items.
I'll make them pay… - Arcade mode: Clear all missions without dying.