Can I run RetroPie under Ubuntu?

I recently bought a RetroPie kit that I have set up and play on in the livingroom and I love it. I was wondering if there was a way to run a RetroPie setup from within Ubuntu 16.04.1 LTS. Can I run it inside of a Terminal window? Can I set up some type of VM to run it in? If inside of a VM, what type of hardware should I set it up to emulate?

I finally figured out the answer to the real question I was asking. "would Ubuntu be taken over by RetroPie, or would it run in a window."

I watched this install instruction video which showed the install, how to run it, and how to escape it and get back to the desktop.

I know the instructions for the install are the same as what was posted already, here and on github, but none of them explained if the GUI would take over my Ubuntu desktop environment or not. I now know that it will run as a normal full-screen app, which you can easily shut down when done playing with it.

I was wondering if there was a way to run a RetroPie setup from within Ubuntu 16.04.1 LTS.

From the official RetroPie download page:

Debian / Ubuntu on a PC

For installation on a PC running Ubuntu please follow these instructions – https://github.com/retropie/retropie-setup/wiki/Debian

The aforementioned link reports everything you need. It is documented very well:

Section 2.1: Download

Update and upgrade the existing APT packages:

sudo apt-get update && sudo apt-get upgrade

Install the needed packages for the RetroPie setup script:

sudo apt-get install -y git dialog

Download the latest RetroPie setup script:

git clone --depth=1 https://github.com/RetroPie/RetroPie-Setup.git

Enter the folder with the setup script:

cd RetroPie-Setup

The script is executed with:

sudo ./retropie_setup.sh

Regarding your second question:

If inside of a VM, what type of hardware should I set it up to emulate?

Why would you want to do that? You are talking about emulating an ARM platform (the Raspberry Pi) and then using it to run emulators for other platforms. That would be not only cumbersome but also quite slow.

I don't see a reason why you should emulate emulators instead of running them directly.

I believe they have instruction for how to install it with a minimal setup of ubuntu as root user. I could not find instructions to install as a regular user. There is some setup procedure used which you can find on the internet to set up retropie on a minimal setup of ubuntu. It may be easier to run it on raspberry pi or odroid by itself without ubuntu where it is just put on an SD card without all the instructions you would have to follow with an ubuntu setup.