great psp game

what would u guys say is a rlly good psp game beacuase i hav had a psp since marach 05 and i havnt ever rlly got into it that much i mean gta took me 2 days to beat does it hav ne good fps shooters out or ne good multiplayer games or i would love if there was some good fps shooters with good online i hav a ps3 also i want something that plays as good as resistance and hopeful has that god of online i dont care that much about looks i just done want it to look like a ps2 game in 1999