https://www.corpsepartypsp.com/
Despite the name, it's a Higurashi-esque horror game, not a kill-em-all slaughterfest. It probably appeals to the same crowd, though, so if you like those kinds of games, you'll probably enjoy this.
I know a lot of you might not want to get it since it's PSN-only, but you'll be depriving yourself of a great experience.
If this sells well enough they'll bring the sequel over, and at $20 it's half the price of a new PSP game, so buy this when it comes out tomorrow!