45. Mass Effect 3
We know, we know, Mass Effect isn't really the same as any of the other games we've listed here, but just think about it. The entire trilogy follows Shepard and his crew trying to thwart those who would see the whole of humanity wiped out entirely. In this, Mass Effect 3 (since it's the last game in the series, and about time to wrap things up) is certainly worthy of being called apocalyptic. You don't get much closer to the death of all sentient beings than the Reapers.