: This indicates the first part of a multi-part 7-Zip compressed archive. How to "Complete" the File
: Use a program like 7-Zip or WinRAR . Right-click only the .001 file and select "Extract Here." The software will automatically pull data from the other parts to create a single, usable .cia file. SMTIVA-USA-(UNDUB)-CIA-Ziperto.7z.001
: Once extracted, the .cia file is typically installed onto a 3DS via the FBI homebrew application or played on the Citra emulator. Context of the "Undub" : This indicates the first part of a
: You must have all subsequent parts (e.g., .002 , .003 , etc.) from the same source in the same folder. : Once extracted, the
Many fans prefer the "Undub" version because they feel the Japanese voice actors provide a more "organic" or emotive performance compared to the English dub. Since Shin Megami Tensei IV: Apocalypse did not originally include dual-audio options, these fan-patched versions are the only way to experience the original Japanese performances with English subtitles on the 3DS. Shin Megami Tensei IV: Apocalypse Review (Nintendo 3DS)
You cannot use the .001 file on its own; it is only a fragment of the full game.