No, you cannot.
There is no ISO file of any Forza Horizon game that will run on PPSSPP. Here’s why:
ISO Name: Test Drive Unlimited (USA).iso
Why it works: TDU on the PSP is a scaled-down port of the legendary PC/Xbox 360 open-world racer. It features:
Graphics Settings for PPSSPP: Enable “Rendering Resolution” to 3x or 4x PSP for near-HD visuals. TDU suffers from pop-in, but overclocking the emulated PSP CPU (in PPSSPP settings) helps.
If you truly want to play the real Forza Horizon, stop searching for a PPSSPP ISO. Instead, use this two-step method:
You might be thinking, "If it's just a mod, is it worth it?"
Absolutely. For fans of the racing genre, these mods offer a unique blend of nostalgia and modern car culture.