Earth.defense.force.iron.rain-codex.part2.rar »

: If you are just starting, prioritize upgrading your Energy Core to improve your mobility and "Overdrive" duration, which is crucial for survival in later missions.

: Once extracted, you will typically find an .iso file or a setup.exe to install the game. About Earth Defense Force: Iron Rain

Because these files are parts of a single larger archive, you cannot "use" Part 2 on its own. To extract and play the game, you need to follow these standard steps for multi-part RAR files: How to use Part 2