This is really a mecha anime, I mean, obviously it is, it's named after the mecha. but in terms of the actual story, the mechs aren't really that important. It has more in common with Asimov than Ideon. The story is actually about time dilation and how much you're willing to spend of the only thing you can never get back. It's ridiculously effective for such a short show, basically everything is properly set up and paid off. A lot of people see this as the precursor to Evangelion but it's much more like a sister show than a parent. It believes with all it's heart in the goodness of mankind