You can run dual boot on a Mac to create a Windows partition for all your games.
You could use the Windows 10 technical preview to get a free copy of windows http://windows.microsoft.com/en-gb/windows/preview-iso
I run dual boot for all my games, translated VN, as well as Steam works perfectly.
There is also parallels but that isn't free and it's needlessly troublesome.
Guide on how to use dual boot on a Mac, I can answer any questions you have on it but you should find it pretty simple.
http://www.macworld.co.uk/how-to/mac/how-run-windows-on-mac-3497251/