There is no game. The 10GB was mostly "padding file" (empty data) to make the file look legitimate.
To reach a size like 10 GB, most non-essential assets are stripped away. This often includes removing all audio (music, dialogue, cutscenes), lowering texture quality to extreme levels, and deleting large sections of the map . gta 5 highly compressed 10 gb work
Many "highly compressed" sites are fronts for malware. These files often include: Hidden inside the "installer." There is no game