Developers often mod existing PSP games (like Syphon Filter or Army of Two ) to look and feel like Resident Evil 4, but these are not the full original game.
CSO is compressed. RE4 as CSO saves ~300MB but increases load times. Use ISO for smoother performance. Resident Evil 4 Download For Android Ppsspp
Open PPSSPP, navigate to the folder where you saved the file, and launch the game. Developers often mod existing PSP games (like Syphon