Forgive me for having played Battlefield 2: Modern Combat, and not Parasite Eve. I cannot detail to you how the upcoming PSP game The 3rd Birthday builds upon the latter. But I can say how wonderfully it echoes the former.
The 3rd Birthday is a PSP adaptation of a Square Enix game originally released for Japanese mobile phones. It now comes to American PSPs in early 2011, following up on Parasite Eve by pitting protagonist Aya against some sort of evil monster infestation that's wrecking New York.
Aya can posses allies or zap into enemies, destroying the bad guys in the process.
For some reason, I've been a fan of body-hopping in games since I did it in Battlefield 2: Modern Combat, a 2005 first-person shooter that let you look at another soldier on the battlefield and warp into their body (the Battalion Wars games on Nintendo systems had a similar mechanic). The system allowed the player to feel as if they could control a squad of troops at once and made a nice meta-game of the challenge of warping from body to body, avoiding enemy fire and finding the best perches from which to shoot.
When Aya activates her Overdrive ability in The 3rd Birthday, she can jump into the character at whom you aim, and, if they are a friendly, assume some of their abilities. (A side perk is that you might pay more attention to the excellently bad names of these guys, such as Duncan Dodgeson.) When she jumps into enemies, an opportunity that appears to be more rare and requires that they are weakened, she kills them.
The body-hopping system doesn't get used in a lot of games. I don't know why, because it's a lot of fun. It appears to work well in The 3rd Birthday which is otherwise a sharp-looking shooter.
The game will be out in 2011. It's one of the next big releases for Sony's PSP.