It's not easy to explain the theories of Friedrich Neitzsche. It's also not easy to get past that level of Megaman that you've been playing over, and over and over again. Put the two together and you just might have some sort of understanding, or at least that's what a series of 8-bit shorts explaining philosophy would hope!!
One theory of Nietzsche's, which drew on traditional ideas within Buddhism, followed the idea that the universe was one with with no end and no beginning, an endless loop of suffering in which one is destined to make the same mistakes forever. See: Megaman!
Nietzsche’s argument against Christianity, as explained above at least, is that it encourages, even celebrates mediocrity and frowns upon excellence. I wouldn't agree that this is our current state, but it's interesting to consider.
Nietzsche respected the scientific method, but he recognized its limitations as a means of describing, rather than explaining the world, as explained in this video above!