This is how to you can turn your Raspberry Pi 2 into a pretty powerful retro console. It runs emulation station and can emulate over 20 consoles right up to the n64 era.
Step 1: What You Need
A raspberry pi 2
A micro sd (I recommend at least 8 gb)
Micro sd reader
Micro USB power supply (a Standard phone charger will work fine)
Usb controller (optional but makes gaming more comfortable)
Ethernet cable (again optional but essential for putting your own games on the device)
Monitor or tv
Step 2: Getting the OS
I got the OS from a website called recalbox, http://www.recalbox.com/ as it was quick and easy to set up and get going.
To download it go to https://github.com/recalbox/recalbox-os/releases and download 'recalboxOS-4.0.0-beta1.zip'
This could take a while (it did for me anyway) but be patient.
Once the zip has finished downloading go ahead and plug your SD into your reader, and then your SD reader into your computer.
Step 3: Formatting the SD Card
Before you do anything you need to make sure that the SD has been completely wiped, to do this you can format it using a variety of different programs. For mine I used https://www.sdcard.org/downloads/formatter_4/ once it has been formatted you can move on to the next step.
Step 4: Extracting the Zip File
To extract the zip file you need to right click the file that you downloaded earlier.
Click extract all.
And then change the location so it will extract onto your SD card.
Step 5: Plugging It All In
That's the hard part done so now just stick the SD into your PI.
Plug the HDMI cable, Ethernet cable, controller/keyboard and power supply into the PI.
Turn your monitor or tv on.
Turn your PI on (make sure you do this last as the PI needs to be able to sense everything upon booting up)
Step 6: Adding Games
Once the PI has booted and the program has finished its initial set-up you should be greeted with a controller config tab, go ahead and set up the controller. Then you should have be able to begin playing the preloaded games.
But if you want to put your own games on, you need to make sure that your Ethernet cable is plugged into your PI and its hooked up to the same network as your PC.
Step 7: Adding Games 2
Make sure your PI is on and connected to WiFi.
Open up the network tab on your pc and you should see your PI underneath the name 'RECALBOX', double click it.
Open 'user data'
Then open the 'roms' file.
Open the console that you have downloaded the games for (if you haven't got any you can get them from www.emuparadise.me )
Drag your chosen ROM file/s into the correct folder.
Go over to your PI and grab the controller.
Hit start, games settings, reload games list.
Your game/s should be on your PI and ready to play.
Step 8: Done!
If you have any problems at all with the program or have a question feel free to drop a comment below.