Files ending in .rar (like "part1.rar") are compressed archives. In the context of "Areal Gamer," this likely refers to a split-archive download from a specific gaming community or uploader.
Based on the components of your query, here is an informative overview of the franchise and common practices for game downloads: Resident Evil Franchise Overview
The series began in 1996 and has since expanded into numerous sequels, remakes, films, and novels.
