We try and try to find a way to automate. I've use 'Silent Install Builder' succesful and also other tools. It's a lot of work but well worth not having to do it by hand in the end.
Silent install builder: http://www.silentinstall.org/. We mostly use the 'Automation script' is really easy once you get the hang of it and works a lot of the time (but not always!).
I've used this many years back to build silent installers. http://www.silentinstall.org/
More recently, I've found SuperOrca to be useful to edit/customize MSI installers for silent or gpo deployment. Ms link: https://docs.microsoft.com/en-us/windows/win32/msi/orca-exe
Direct download: https://www.technipages.com/downloads/OrcaMSI.zip
Yes, well I have some games that aren't on Steam and come in the form of executables. FEAR: Combat, for example.
I found Silent Install Builder and a way to generate a response file for InstallShield / MSIs: http://helpnet.installshield.com/installshield18helplib/IHelpSetup_EXECmdLine.htm#wp1039936