Contra 4/Secrets

Konami Code: Upgrade Weapons
When you have collected a weapon or two, press and enter the Konami Code:, , , , , , , , , ,. Be careful not to enter it again or you will die, but after a continue you can enter it again safely.

Classic Contra Codes
Here are the cheats for the unlockable NES games, the original Contra and Super C.

Unlockables
To unlock Challenge Mode you need to beat the game on any difficulty.