If you want a stable, high-performance racing experience on your mobile device without the potential bugs of a fan mod, these official PSP titles are the best alternatives to Forza Horizon :
The only true open-world racing game on the PSP. It features over 1,000 miles of road and a deep car collection system. Forza Horizon Iso Ppsspp
A unique off-road racer that captures the "festival" vibe of early Forza Horizon games. How to Play Racing ISOs on Android/iOS If you want a stable, high-performance racing experience
Fan-made ISOs often feature a redesigned main menu and HUD that mirrors the signature look of recent Forza titles. Best Official Alternatives for PPSSPP If you want a stable
Many mods include custom texture packs to improve road surfaces, skyboxes, and lighting.