Games similar to Resident Evil might offer a comparable experience. Look into other survival horror games available on portable devices.

If you're looking to legally obtain Resident Evil 4 for PSP:

Resident Evil 4 is one of the most iconic survival horror games ever made, but it was never officially released for the PlayStation Portable (PSP). However, thanks to a dedicated modding community, fans can experience a "better" version of Resident Evil 4 on their handheld devices through impressive fan-made projects.

Downloading copyrighted material without owning the game or having permission from the copyright holder is illegal. However, if you're looking for information on how to obtain a copy of the game you already own, there are legitimate ways to do so.

In this guide, we’ll explore the history of RE4 on PSP, why an “official” ISO doesn’t exist, how to achieve the best (aka “better”) playing experience, and the legal and technical steps to get Leon S. Kennedy’s Spanish nightmare running on your handheld.