0451 Vault - System Shock 2 (1999)

Oddly enough, while 451 appeared first in System Shock (1994), people mostly remember it for being in Deus Ex. System Shock 2, being a sequel to System Shock obviously had to have featured it in some form. It’s a bit of a variation on the code, but it’s still good old 451. And it’s even a door code.