Konami Code — 30 Lives

Gradius · NES · 1986

Entering Up, Up, Down, Down, Left, Right, Left, Right, B, A at the title screen grants the player a full set of power-ups — the origin of the most famous cheat code in gaming history.

Kazuhisa Hashimoto, the programmer responsible for porting Gradius to the Famicom, created the code because he found the game too difficult to test in its default state. He programmed a shortcut that granted the player all power-ups simultaneously, intended only for internal use during development, but accidentally left it active in the final retail cartridge. The code became public knowledge almost immediately — whether through word of mouth or gaming magazines — and Konami subsequently incorporated it into dozens of their titles. Its most famous appearance is in Contra (1988), where it grants 30 lives and transformed an impossibly hard game into something a casual player could finish.