Warning: This version runs at a low framerate, has no sound in certain areas, and crashes during the final boss. It is not the “top” experience.
Here’s the confusion source: the PS Vita (PSP’s successor) has a vibrant homebrew scene. Developers created an unofficial Undertale PS Vita port using the "EasyRPG" engine. It runs decently. undertale psp iso download top
But for PSP? No. If you truly want "Undertale on a Sony handheld," the PS Vita is your only legitimate hardware path. Warning: This version runs at a low framerate,
If you’re still determined to search, use these red flags: has no sound in certain areas