Large games are often split into smaller "parts" for easier downloading. To access the game, you must have all parts (part1, part2, etc.) in the same folder and use software like WinRAR or 7-Zip to extract them simultaneously.
The specific file name you mentioned typically appears in the context of third-party distributions or "repacks": Republique.Remastered.Fall.Edition.part1.rar
Players assist a young woman named Hope as she attempts to escape an oppressive, totalitarian facility known as "Metamorphosis". Large games are often split into smaller "parts"