Spaceengine.v0.990.45.1940.part03.rar -

If even one part (like part01 or part02) is missing or corrupted, the entire installation will fail to extract.

Because this is part of a split RAR archive (indicated by .part03 ), you cannot open or use it as a standalone file. Here is the essential context regarding this file type and the software: What is this file? SpaceEngine.v0.990.45.1940.part03.rar

Files with this specific naming convention—especially those found on third-party file-sharing sites or forums—are often associated with of the software. If even one part (like part01 or part02)

Downloading split RAR parts from unofficial sources carries a high risk of containing malware or bundled "adware." SpaceEngine.v0.990.45.1940.part03.rar

The string v0.990.45.1940 identifies a specific beta or early-access build of SpaceEngine. About SpaceEngine

It uses real astronomical catalogs for known objects (like the Milky Way, nearby stars, and exoplanets) and procedural generation to fill in the rest of the observable universe with billions of galaxies and star systems.