10 Creepy Secrets Behind Classic Video Games

10. The Zombies' Screams Are Actually Cries For Help (In Reverse) - Half-Life 2

Half-Life's common zombie enemies aren't especially creepy on their own, shambling around clumsily at low-speed such that even unskilled players shouldn't have too much trouble taking them down in small numbers.

But there's a horrifying secret ingeniously hidden within the blood-curdling screams of Half-Life 2's zombies - which, remember, are poor humans who've had headcrabs attach themselves to their heads to use them as hosts.

If you take the zombie's seemingly nonsensical screams and play them in reverse, it reveals that they're actually screaming "Oh god, help me, please help me!"

Granted, the zombies don't exactly sound like they're having a whale of a time when listened to in-game, but this confirms that the poor victims of the headcrabs are entirely conscious of what they're being made to do - and worse, what you're doing to them.