Its the background for the Mass Effect 3 Title screen. it represents when the Reapers came from Dark Space to cleanse the universe in their next cycle of consumption. They attacked Earth in force at the very beginning of the game because Shepard(your character) killed their scout in the first game.. it pissed them off. There is actually a cut scene called Leaving Earth on YT. Its super sad but the emotion and drive is given at the beginning of the game and youve already invested a lot of time in the first two games. My favorite part of the scene is the score and how they sequenced fear, hope, futility, and insistency in every note....