Your PSP must be running CFW (such as PRO-C or LME) to execute homebrew applications.

Ensure the game folder name does not contain strange symbols or spaces. Keep it simple, like "UndertalePSP".

There are no shortcuts to the Underground.

Extract the folder on your computer. You should see a folder containing an EBOOT.PBP file and additional asset folders (audio, data, graphics).

Create a new folder (e.g., Undertale ) and place the EBOOT.PBP file inside it.

If a website forces you to complete a survey or download a separate "password text file" to unlock the Undertale ISO, close the tab immediately.

Working battle systems, movement within early areas like the Ruins.

However, the homebrew community has stepped in to bridge the gap. Enthusiastic developers have built unofficial, fan-made versions of Undertale specifically tailored to run on PSP hardware and the PPSSPP emulator. Top Methods to Play Undertale on PSP

If attempting to use an emulator (like PPSSPP for PSP), ensure:

Download the project file, which is typically compressed in a .zip or .rar format.

Connect your PSP to your PC via USB. Navigate to the PSP directory, open the GAME folder, and drop the entire Undertale folder inside.

Ensure your PSP is running Custom Firmware (CFW) such as PRO-C or ME. Connect to PC: Connect your PSP to your computer via USB. Locate the Folder: Go to PSP > GAME .

The Undertale PSP Edition (often found on itch.io) is popular, along with active community-driven ports like PortableTale .

If you need assistance setting up your console, let me know: What do you have (1000, 2000, 3000, or Go)? Is your PSP already running Custom Firmware ?

Here's the key distinction: For proper Undertale emulation, you'll need to play the of the game on a portable device like a Steam Deck, laptop, or tablet. The PSP simply can't natively run PC game files, and converting an Undertale PC ISO to PSP format isn't technically possible.

: Disconnect from the PC, go to the Game menu, and select the Memory Stick to find your Undertale port. Where to Safely Find PSP Homebrew