Parallels: What the heck is it and how do I install it on an external HD?

Pretty much what the title says. Boot Camp won't work for me because the HD on the MBPR is only 256GB which isn't enough for a Windows partition for me to keep my games on and apparently many games can't be stored on an external HD and used with Boot Camp. I Paralles it's a way of using Windows and have heard you can install it on external USB 3.0 HDD with good speeds but that you can't "boot into Windows"... But if I can't boot into Windows how do I access it?

Also, can anyone speak from experience of otherwise whether I would be able to play games without lag with Parallels (as well as the games) installed on a USB 3.0 external HDD?

Edit: Typo in the title *facepalm*

 

I assume you were missing the word it on your title Parallels: What the heck is and how do I install it on an external HD?

If that was the case, it's fixed.

Anyways, moving on to parallels, parallels runs windows in a virtual machine so gaming performance will suck no matter what you do.

 

Okay, how about this. According to this thread Steam works just fine from an external HDD on Boot Camp. I have no problem buying my future games through Steam but I have several games that I downloaded from Amazon, Gamestop, etc. I've seen that I can add these to my Steam library but would that just create a short cut or would it actually add it to my library so I could play it from the HDD?

 

When you add a non steam game, it just creates a shortcut, nothing more.

 

you can put your steam folder on the external HDD and create shortcuts to the games or a single shortcut to steam