Since there is no official port, these "ISO" files are total conversion mods. They allow players to experience a version of GTA 4's atmosphere on the PPSSPP emulator.
The PSP simply did not have the hardware power to run GTA IV. The game required high-definition textures, complex physics (the iconic Euphoria engine), and a massive draw distance. The PSP’s 333 MHz processor and 64 MB of RAM would have exploded trying to render Liberty City. gta 4 iso file for ppsspp