Game developers are a clever bunch, and its quite common for them to leave little secrets in their games for the dedicated gamers out there. And sometimes, theyre absolutely brilliant. Like a space marine screaming Game over man! Game over! in a beautiful reference to the film Aliens. For this list, were going to keep it to one entry per franchise, because the Halo series has about 20 per game, and it would be a little unfair to the rest.