Files below 100MB for a 3D PS2 game (e.g., God of War II ) are almost always fake or viruses.
These are "highly compressed" by manually removing "dummy data," high-quality FMV (Full Motion Video) cutscenes, or multiple language files to shrink a 4GB game down to a few hundred megabytes. Notable PS2 Game Sizes i--- Ps2 Highly Compressed Games Iso