Classic Windows 3.1 games
Windows 3.1 was the first Windows software (by Microsoft, of course) that became popular worldwide. Contrary to popular belief, Windows 3.1 wasn't a full operating system. It was a collection of applications running in an operating environment, and yes, there's a big difference. Why? Because to run Windows 3.1 you still needed an MS-DOS based computer.
The need of MS-DOS was perhaps the main reason why games that ran under Windows 3.1 weren't so many. In fact, most of them are little more than puzzle games, card games and simple strategy games. That doesn't mean Windows 3.1 lacked good games; in fact, a few of them are still very much enjoyable today.
As you can imagine, backward compatibility is a problem. To run these games you need a virtual machine or, if you like the challenge, you could install Windows 3.1 on DOSBox. On archive.org you can even play a few Win 3.1 games online directly in your browser.