- Mana Khemia: Student Alliance (really one of my highest recommendations, not just even on PSP. The best "magic school" game out there, imho)
- Metal Gear AC!D
- Patapon
- Pixel Junk: Monsters
- Neverland Card Battles
- Monster Hunter Freedom Unite
- Metal Gear Solid: Peace Walker
- Aegis Eclipse: Generation of Chaos
- PoPoLoCrois
- Dynasty Warriors 2
- Lunar: Silver Star Story
Honestly, I could do an entire separate comment of just RPGs, there were SO many good ones for PSP.