Windows 10... games

Windows 10 generally because DirectX 12 will be exclusive for it.

However, older games may not be compatible with Win 10. So if there is an older game you want to play you might want to Google it to check if it will or will not work with Win 10. An example could be Fallout 3. It was designed for Windows XP, but it can run in Win 7 and Win 8 with some tweaks. Initially people could not run that game in Win 10, but I think a couple of solutions were found to allow it to run.