If you are asking because you are having trouble with this specific file:
Ensure the version number ( v2415920 ) matches across all downloaded parts. Generation Zero v2415920.part08.rar
Generation Zero is designed for 4-player co-op; unofficial versions usually cannot access official multiplayer servers [5]. Troubleshooting Archive Issues If you are asking because you are having
Multi-part archives (like .part08.rar ) frequently fail to extract properly if one part is missing or corrupted [2]. Generation Zero v2415920.part08.rar
These are the standard tools for opening .rar files.