: This file cannot be opened or used on its own. You must have all other parts (part1, part2, part3, etc.) in the same folder to extract the game files.
: .part5.rar means this is the fifth piece of a larger download. Because games are often dozens of gigabytes, they are frequently split into smaller "parts" (e.g., part1, part2, etc.) to make downloading more manageable. Important Usage Notes: ELEX.II.v1.03.GOG.part5.rar
: Once extracted, this archive usually contains the GOG offline installer (an .exe file and several .bin data files). : This file cannot be opened or used on its own