10 Hidden Video Game Sequel Clues You Totally Missed

9. A Hidden Room In Batman: Arkham Asylum Laid Out Arkham City's Plot

Batman: Arkham Asylum featured an ingeniously well-hidden Easter egg which provided a cryptic hint at the direction of the eventual sequel, Batman: Arkham City.

In Arkham Asylum Warden Quincy Sharp's office, you can use Batman's explosive gel to uncover a second, secret office hidden within the walls.

Inside, there's a giant blueprint map of Gotham City, outlining Sharp's proposal to turn the slums of Gotham into one giant asylum.

This effectively forms the plot of Arkham City, with Batman being thrown into the titular super-prison and having to battle his way out.

It's an especially shocking and easy-to-miss Easter egg given that the secret office doesn't appear on any maps and isn't visible in detective vision.

In fact, it went undiscovered for almost an entire year before Rocksteady revealed the secret on a podcast mere days after Arkham City itself was announced. Incredible.