You need the PPSSPP app installed on your device.
: PPSSPP handles PSP games like God of War: Chains of Olympus and God of War: Ghost of Sparta . It is technically impossible for it to run Ascension . God Of War Ascension Ppsspp Zip File Download
Use an app like ZArchiver (Android) or WinRAR / 7-Zip (PC). You need the PPSSPP app installed on your device