Using an Android device or a Java emulator (like J2ME Loader) on a hacked PSP, you can play this official "highly compressed" version. It lacks the tension of the original, but it’s 100% stable and legally obtainable.
To run any "highly compressed" RE4 fan project, you will need: A PSP (1000, 2000, or 3000) or a PSP Go. (like PRO-C or LME). A fast Memory Stick (at least 1GB). resident evil 4 psp highly compressed
Developers in the community have created "fan ports" based on the Resident Evil 4: Mobile Edition (originally for iOS/Android), modified to run on PSP homebrew. Using an Android device or a Java emulator