Since it isn't on PSP, you have these official and community-tested options:
The PSP version of God of War: Ascension is a unique experience that offers a different take on the God of War series. While it may not have received the same level of attention as its PS3 counterpart, the PSP version still provides an exciting and challenging experience for fans of the series. god of war ascension psp iso link
To ensure that God of War: Ascension runs smoothly on your PSP, make sure your device meets the following system requirements: Since it isn't on PSP, you have these
To reduce lag on mid-range Android devices, try these PPSSPP settings: Since it isn't on PSP