God of War: Ascension is a PlayStation 3 exclusive and is not available for the PSP or the PPSSPP emulator. Any downloads claiming to be a "highly compressed" version for PPSSPP are unofficial and potentially unsafe.
If you own a physical copy of the game, you are legally allowed to create a "backup" ISO. If you are looking for compressed versions online to save data, you must be cautious about the source. god of war ascension ppsspp download highly compressed
Q: Will a Snapdragon 680/MediaTek Helio run God of War? A: Yes. Both PSP God of War games run perfectly on even budget phones (Snapdragon 660 or higher) using default PPSSPP settings. God of War: Ascension is a PlayStation 3
Conclusion
Since it is a PS3 exclusive, you cannot run it on a PSP emulator. Here are your actual options: All God Of War Games on PSP If you are looking for compressed versions online