All Working Contra 4 Cheats - DS

Upgraded 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

30 Lives in Original Contra
It's still the same Konami Code, except that A and B are replaced with B and Y, respectively. Input at the start screen of the original Contra game, then press [Start] to begin the game with 30 lives.

[Up], [Up], [Down], [Down], [Left], [Right], [Left], [Right], [Y], [B] - 30 Lives in Contra

Challenge Mode
Complete the game on any difficulty to unlock Challenge Mode.

Unlockables (in Challenge mode)
Contra (NES) - Beat 4 challenges in Challenge Mode
Contra 4 DS Promotional Comics - Beat 32 challenges in Challenge Mode
Contra III Comic - Beat 24 challenges in challenge mode
Extras Museum and Sound Gallory - Beat 40 challenges in Challenge Mode
Jimbo & Sully - Beat 36 challenges in Challenge Mode
Lucia (Character) - Beat 20 challenges in challenge mode
Nobuya Nakazato Interview - Beat 16 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

Sound Test In Super C
To access Sound Mode in the unlockable Super C, as the game's logo is fading in on the title screen hold [Y]+[B] and press [Start].

Unlock Sound Test
Complete all 40 challenges in Challenge Mode.