Using Linux there isn't a lot of choices for fancy Android emulators. AFAIK the only real contenders are Genymotion and the SDK Android Simulator. Personally I've never achieved great performance out of the Simulator so that leaves Genymotion. And that's where I'll start.
Genymotion is an Android emulator which uses VirtualBox s it's core. It seems to be mainly aimed at developers with a pay to use model. However they do offer a free for personal use build. This is the version I will be using for this post.
One of the main issues with Genymotion is it's emulation is based on x86 CPU only, meaning there is no ARM CPU compatibility out of the box. This also means most apps in the Play Store will not work. And speaking of the Play Store is the next issue, the suite of Google apps are not installed by default. This means no Play Store. But don't fret, you can add both ARM binary translation and all your favorite Google apps to a Genymotion Android virtual devic…
I had the problem when loading my Hack Mac that the wi-fi card always grabbed onto en0 and my built in ethernet always defaulted to en1. This cause all kinds of problems with using Apple's internet based services like the App Store, Facetime, and iCloud. These services require your built in ethernet port to be en0. To make the swap I had to go in and delete the following 2 files.
Next we'll decompress the source. Don't forget to enter the directory the archive decompresses to before you run the compile command.
tar vxfj mednafen-<version>-wip.tar.bz2
And then compile the Mednafen source ./configure && make && sudo make install
After it finishes compiling and installing it's binaries you can fire it up by opening a terminal (yes, its a terminal based program. NO built in GUI) and typing in 'mednafen <rom name>'. The list of supported systems is staggering. Refer to the Mednafen homepage for the run down on what all it can do.