Looking Glass Code (0451)

“The door code of Looking Glass Studios, often used in their and other studios’ games as an easter egg.”

Also Reddit:

“TIL that the code 0451 shows up in so many video games because that was the door code to Looking Glass Studios in Cambridge, Massachusetts, and they kept using it in their games. It has since become a running joke.

The full list as far as I know: System Shock, System Shock 2 and Thief (the three LGS games), Deus Ex, Deus Ex: Invisible War, Deus Ex: Human Revolution, Deus Ex: The Fall, Deus Ex: Mankind Divided, Deus Ex GO(what the fuck is this), Sanitarium, Bioshock, Bioshock 2, Bioshock: Infinite, Gone Home, Firewatch, The Novelist, Dishonored, Dishonored 2, and Prey (2017).

In Deathloop, you unlock a trophy using this code on any vault”