How should I add Windows to my Mint PC?

If you have a spare drive, that’s the simpler route. Install Windows to that drive with the Mint drive disconnected, then reconnect it. You can pick which drive to start from in your firmware’s boot menu. That reduces the chance of the Windows installer changing Mint’s boot setup.

You usually don’t make a small boot partition by hand. Windows Setup creates the system partitions it needs on the drive where you install Windows. If you’re sharing one drive, back up first, make unallocated space by shrinking the Mint partition, then point Windows Setup at that space. Don’t select or format the Mint partitions.

Installing Windows after Mint can change which boot entry starts by default, so you may need to choose Mint from the firmware menu or repair its boot setup afterward. Keeping both systems in the same UEFI mode helps avoid extra boot confusion.

For a few games, first check whether they’ll run under Linux. If they do, that avoids repartitioning entirely. A Windows virtual machine is another possibility for some software, but games that need direct graphics performance or particular anti-cheat support may not work well that way.