Contra 4 Cheats

Upgrade Weapons
Enter the Konami code in the pause menu to upgrade your weapons fully. Note that this code can only be used once per life (doing it again will kill you) and that it can only be used in Normal or Hard mode (easy gives you full upgrades automatically)

Up, Up, Down, Down, Left, Right Left, Right, B, A, Start: Upgrade weapons fully

Challenge Mode
Complete the game on any difficulty to unlock Challenge Mode. This includes Easy.

Challenge Mode Unlockables
Contra (NES): Beat 4 challenges in Challenge Mode
Probotector: Beat 12 challenges in Challenge Mode
Sheena Etranzi: Beat 28 challenges in Challenge Mode
Super C (NES): Beat 8 challenges in Challenge Mode

Unlockable Contra 3 Characters
To unlock characters from Contra 3 fame, complete 36 challenges in Challenge Mode.

Unlockable Sound Test
To unlock an in-game sound test, complete all 40 challenges in Challenge Mode.

Unlockable Bonus Artwork & Content
To unlock bonus artwork and other content to be seen at the Contra Museum, complete all 40 challenges in Challenge Mode.