You can only get Windows 10 for free if you already have a license for Windows 8 or Windows 7.
Regarding your linked article:
Virtual machines (Parallels, VM Ware Fusion) are not suited for gaming, since they emulate virtual hardware for the guest system on the host system which takes a large part of the computer's performance.
Runtime systems like Wine (or CrossOver, which shares a great part of its sourcecode with Wine) may work well, see here. But it is a bit tricky to get programs to work and some do not work at all. Best thing about Wine is that it is free and that you do not need a Windows license.
Finally, Boot Camp is Apple's boot manager and only creates a normal dualboot system. Since it is a normal Windows installation, all Windows programs work, but you have to choose wich operating system you want to boot when starting your computer.