Red Alert 2 is from before the release of WinXP though... maybe try the earlier compatibility modes?
@beta001 wrote:but I can't add another monitor as the grey box appears.
^ Not really sure what you mean with that...
See in the guide usually there should be a grey box that says "Another display not detected" but I don't have that box in screen resolution options which would usually fix the menu option and running in earlier compatibility didn't work ☹️
Strange. It shows up right away when I try it. I'm on Win7 Ultimate Edition.
