Classic Windows XP/98/95 games
At the end of the DOS era, PCs started to use the latest Operative Systems from Microsoft. Starting from version 3.1, Windows became very popular and more and more software houses began to create games for Windows.
The first games for Windows 3.1 weren't very popular; there were solitaire card games, puzzle games and little else. With the release of Windows 95, 98 and Windows XP, the Microsoft OS became central in the development of mainstream video games like Age of Empires and the Civilization series.
Unfortunately, backward compatibility quickly became a problem: run an old game on Windows it's tricky; it's easier to run a game made for DOS using a MS-DOS emulator. The only safe and sure way to play old Windows games on recent PCs is to install them directly on an older version of Windows or, if you know how, install and configure a Virtual Machine.