It sounds like you're referring to a split archive file (part of a multi-part .7z set) for God of War: Ascension , specifically from a repack labeled "Gnarly Repacks" .
Select "Extract Here" or "Extract to [Folder Name]." The software will automatically detect .009 and all other parts to piece the game back together. Why Choose a Gnarly Repack? God of War Ascension -Gnarly Repacks-.7z.009