Linux mint is a stable distro that I would recommend to beginners. Or maybe Nobara or Bazzite would be a good choice too. Use whatever distro you like most.
All you really would have to do after installing your distro is to install Steam and enable “Steam Play” in settings. It allows Windows games to run on Linux. Then you install Civilization V through Steam as normal and when installing Guild Wars 2 you can use Steam as well. Run the installer as a non-steam app and install it. Then run the game exe through Steam once it’s installed.
There should be good guides online (YouTube or Google) for installing Linux Mint alongside Windows.
Once you have your system installed feel free to let me know if you need help with Steam and getting the games running
What makes it appealing imo is the immutable aspect. It makes it much harder to break which is what the average user needs. And Distrobox is now included by default which makes it possible to install whatever packages you need inside a container.
The Steam controller 2 will be releasing soon if you want trackpads and extra buttons. I also think Valve is licencing to third parties. IIRC 8bitdo will make a Steam Controller