So, they've recently remade the first Halo game and are currently making Halo 4. In the remake, there are several terminals that reveal some of the backstory of the game and events that take place during the game but away from your point of view. Allegedly, at least some of these hint at the events of the forthcoming game. In one of the videos, a ship from an unknown species crashes on the installation. Take a look at this picture of it from the Halo wiki. Look familiar?