While Gradius may be the first appearance of the Konami Code, its inclusion in Contra is what made the code a household name.
Contra is obnoxiously difficult. So, in order to beat it, you could either get obnoxiously good or cheat. Let’s be real, we all cheated by entering the Konami Code at the game’s title screen to grant us an extra 30 lives! In all honesty, sometimes that isn’t even close to enough to make it to the end.