ElSchorscho

Solved. Believe it or not, after having re-downloaded the file several times, I tried a re-download using another internet browser (Edge instead of Firefox). Works now. Guess Firefox somehow corrupted the .msi file.

Trying a first time installation of the launcher. After upsetting Windows Defender, I allowed the .msi install file to continue. Then, without any further progress, I'm getting this error, which essentially says "This installation package could not be opened. Please have the application's developer check whether it is a valid Windows installer-package." My system: Windows 10 Home x64, AMD Ryzen 5 2600, 16 GB RAM. No anti virus, firewall or malware software other than Windows Defender and Windows Firewall. No RivaTune, TuneUp, Nvidia or any other mumbo-jumbo software running or installed. Unfortunately, the game's full download was apparently taken down so I can't even get around the launcher. ETA: Also I'm unable to apply any compatibility settings or even run as admin, because the checkboxes are gray and deactivated.