Secret levels used to be something extremely special. Before the Internet, you had to either find them on your own or hear about them from the weird kid at school who spent recess picking his nose and staring at the sun. And once you did find out about them, all you wanted to do was brag about your new found knowledge. Let's salute the greatest secret levels in videogame history.

10.

It's hard to bring out something weird and unexpected in a WWII game where Hitler's dead and you're fighting with lightning-zappers, invincibility devices, and time-travel – but then again, giant ants? Disbelief only suspends so far! It ends up feeling like Red Alert with Zerg, except with a lot more people saying "At once!- and "Affirmative!- over and over. The ants add a huge new challenge to the gameplay, where you have to radically change your strategy just to survive. Even then, it's hard as hell. So if you ever travel back in time and kill Hitler, remember to bring a giant can of Raid, okay?