Downloading pirated games, especially from unknown sources, carries a high risk of malware infection. Ensure your antivirus software is active.
Once all files are downloaded, right-click on the ...part1.rar file and select "Extract Here" (using software like WinRAR or 7-Zip). The software will automatically use the other parts to rebuild the complete file. CrisisCoreFinalFantasyVIIReUnion.part1.rar
This file name suggests it is part of a compressed download for the game Crisis Core: Final Fantasy VII Reunion . Multipart archives (part1, part2, etc.) require to be in the same folder to successfully extract the contents. What to do: Downloading pirated games