I am trying to install gvim81.exe on multiple computers. The /s switch isn't working and /? doesn't give any results. Does anyone know how to silently install this version?
You can consider to use a gvim msi package, e.g. from https://github.com/petrkle/vim-msi/releases.
msiexec supports a wide variety command line options.
/passive seams to be one you are looking for (https://docs.microsoft.com/en-us/windows/desktop/msi/standard-installer-command-line-options).
msiexec /package vim-8.1.55.msi /passive