rootsupd = Update for root certificates.
rvkroots.exe = Update for the repository of revoked root certificates, the ones that should no longer be trusted
Both files are from MS, but the download links vanished into oblivion.
A note on VC++ 2015: The new VC++ 2017 will NOT add to the bunch but will actually replace VC++ 2015 completely. Since a VS 2017 RC just appeared, this will be soon. The game should run also with VC++ 2017.
Microsoft update catalog: http://catalog.update.microsoft.com/v7/site/
Windows Install media creator: https://support.microsoft.com/en-us/help/15088/windows-create-installation-media