Standard ISO files for PlayStation 2 games can exceed 4GB. Highly compressed versions use advanced ripping techniques to strip non-essential data, bringing the file size down significantly (often under 1GB) while keeping the core gameplay intact.
Use (on PC) or UMDGen to convert .iso → .cso with compression level 9. This shrinks a 1.4 GB PSP game to ~700–900 MB, still playable on PPSSPP. god of war 2 highly compressed for android ppsspp extra new