Contra

Contra is responsible for history's most famous cheat code: the Konami Code (up, up, down, down, left, right, left, right, B, A) granting 30 lives — necessary given the game's brutal difficulty. Two co-op players shot through eight levels inspired by Alien and Rambo, with the Spread Gun as the supreme weapon everyone wanted and nobody wanted to lose. Co-op was the definitive NES experience: two friends on the couch against impossible enemy hordes.