: Because the game files were large, they were often split into smaller "parts" (e.g., .part1, .part2, .part3) for easier downloading or sharing. You need all parts in the same folder to successfully extract the contents using a program like WinRAR or 7-Zip .
For a look at the gameplay content featured in the final stages of development, you can watch this walkthrough: Chernobylite.Final.Stage.Early.Access.part3.rar
The file appears to be a segment of a compressed archive for a pre-release build of the survival horror RPG Chernobylite . Here is what this specific file represents: : Because the game files were large, they