Matrix Games Forums

As well as the main exe file for v100, I also have 3 other files for v100.2, v100.3 and v100.4. These are not, however, exe files.

Sorry to be dumb but what do I do with them?

The EXE file is not actually the executable for the game itself. This is what is called a self-extracting compressed file, like a ZIP file. It's essentially a ZIP file with a little embedded ZIP extractor so you don't necessarily have to have such a program installed on your computer. Furthermore, in this case, the ZIP file is divided into 4 parts.
 
Running the EXE file will automatically decompress the game files, combining the four parts, and then at the end it will start the install program for you.
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Extract all the files to a temporary location, then run the .exe file to install the game. We have to split up the installer this way for large installers to prevent some anti-virus/security software from stalling the installation.

To further refine Erik's statement, we have been cautioned to extract all the files to the SAME location, then run the .exe file.