I'm actually a huge fan of the ending. The loss of gravity, the crystallization of Cocoon, the animals bursting into dust, and the actual end. It came together pretty well for me there. But I do think I'm in the minority on this one.

If I were to give a mid-game scene. I'd go with Snow at Hope's house, risking his life and all that jazz. Or the first time we see Shiva in action.