One of my favorite, unexpected gems was Kenka Bancho. You’re a bancho (high school delinquent badass) and you have 7 days during a school trip before graduation to punch other school banchos into submission to prove you’re the best of all banchos. A real shame that only one game got localized, there are several others in the series.

I was also sad that Maverick Hunter X didn’t get sequels, so it became the sole 3D remake of Mega Man X, but it’s really good and you can even play as Vile. Speaking of Capcom, you could also play Monster Hunter 1, 2 or 3 on your PSP. I spent a significant amount of time on 2 and got nowhere near the mid game. I kept getting my ass handed by some bosses. Kushala Daora became my arch nemesis. On the other hand, beating Basarios was a piece of cake with bow and (piercing) arrow