Since Injustice: Gods Among Us did not have an official release on the PlayStation Portable (PSP), the version you are playing on PPSSPP is likely a high-quality mod of Mortal Kombat: Unchained.
, typically built using the engine of another fighting game like Mortal Kombat: Unchained WWE All-Stars Official Portable Versions vs. PSP Mods Official Handheld (PS Vita): Ultimate Edition injustice gods among us ppsspp exclusive
Does Injustice: Gods Among Us PPSSPP Exclusive exist as an official product? No. Sony never released it. Warner Bros never coded it. But as a community passion project, a "demake" using the bones of Mortal Kombat, and an offline alternative to the microtransaction-hell of the mobile game? Yes, absolutely. Since Injustice: Gods Among Us did not have
Download the PPSSPP ROM (fan-preserved): injustice_gods_among_us_ppsspp_exclusive.iso
Requires PPSSPP 1.15+ with “Block Transfer Effects” enabled. But as a community passion project, a "demake"
Download PPSSPP Gold from the official website (or the free version from the Google Play Store/Apple App Store). The Gold version is a one-time donation that adds a dark theme and higher-resolution texture support, which is vital for the Injustice mod.