From the company that brought you some of the Clock Tower games,NightCry and helped with the first Tekki / Steel Battalion game, KONAMI gives them five cheeseburgers to make the best PSP game ever.
They make what is essentially the adaptation of another manga / anime(can't remember exactly) and put mecha in it. It looks like EVangelion but it's not, the similarities are insanely superficial.
The gameplay consists of the hero doing something mundane which involves talking and doing RPG shit, the second phase is the aliens attacking and you going out on the field and fighting aliens, saving civilians, gathering intel etc and then going back to the HQ to give out an accurate report that will move you to the third phase : the giant mecha battle. Then plot happens, the episode ends and you watch an ending as if in anime. Then, after you save the game, the next episode starts with an opening. No joke. Unfortunately the game is very much on the cheap side, 30FPS etc you know the drill but since it's on the PSP you can emulate it(I don't think you can buy it anymore anyway) and it's really worth it for those who like mechas and the whole ground level fight before having the big climatic giant battle.