Halo

In the 26th century, humankind has colonized hundreds of worlds in Earth's interstellar neighborhood, only to stumble upon a hostile alliance of aliens known as the Covenant. Motivated by their Prophets' promises of ascension to godhood in the form of the eponymous Halos, a series of ring-shaped superweapons built by the ancient race of the Forerunners, the Covenant are bent on humanity's destruction.