Upgrade all weapons:
To fully upgrade all your weapons, pause the game and press Up(2), Down(2), Left, Right, Left, Right, B, A, Start. Note – This code can only be entered once per level; repeating it will cause death. Also, you must have an upgradeable weapon or else you will die. This does not work on Easy difficulty.
To get 99 lives, lose a life at the exact same time you gain an extra life. To easily accomplish this, defeat the mini-Boss in Level 1 and you will get an extra life. Get hit by one of the fireballs it shoots immediately after destroying it.
To unlock Challenge mode, beat the game.
Challenge mode bonuses:
Unlock the following bonuses by completing the corresponding numbers of challenges:
BONUS – NUMBER OF CHALLENGES
NES Contra – 4
NES Super C – 8
Probotector character – 12
Nobuya Nakazato interview – 16
Lucia character – 20
Contra 3 comic – 24
Sheena Etranzi – 28
Jimbo and Sully from Contra 3 – The Alien Wars – 36
Sound Test option – 40
To play with an alternate color, beat the game. Then, at the character selection screen press Up or Down.
To view an alternate ending, beat the game on Normal or Hard.
30 lives in NES Contra:
To get 30 lives in NES Contra, before the demonstration begins at the Contra title screen, press Up(2), Down(2), Left, Right, Left, Right, Y, B, Start.
Hard mode in NES Contra:
Beat NES Contra to unlock the Hard difficulty setting for it.
10 lives in NES Super C:
To start with 10 lives in NES Super C, at the title screen, press Right, Left, Down, Up, B, Y.
Sound test in NES Super C:
To unlock the Sound test option in NES Super C, as the game’s logo is fading at the title screen, hold Y B and press Start.