A version of the game originally made for older mobile OS styles, wrapped in an ISO format to run via emulation.

Since RE4 is not a PSP game, you cannot run a standard ISO on PPSSPP. Instead, use these alternatives: PS2 Emulation (Recommended) : Use a PS2 emulator like or NetherSX2. You will need a legal Resident Evil 4 PS2 ISO (approx. 4GB) and a PS2 BIOS file. GameCube Emulation Dolphin Emulator to run the original GameCube version of RE4. Resident Evil 4 Mobile (Android)

: "Highly compressed" files (e.g., promising a 40GB game in just 100MB) are often used to distribute malware or lead users to survey scams.