You generally cannot open "Part 3" by itself. You must have all parts (Part 1, Part 2, etc.) in the same folder.
It looks like you are looking at a for a repack of the game BONELAB . Since this is Part 3 , here is what you need to know to handle it correctly: Important Notes for Repack Archives: BONELAB [ScOOt3r Repacks].part3.rar
Repacks from unofficial sources can be risky. Always ensure you: You generally cannot open "Part 3" by itself