You can either install a stable version of EmulationStation from a pre-made package, or compile the bleeding edge developer version.

Install the latest stable package.

Download and install the Debian package, either 32-bit or 64-bit.

Configure EmulationStation.

Or, compile the latest version yourself.

Make sure everything is up to date

sudo apt-get update
sudo apt-get upgrade

Install dependencies

sudo apt-get install -y libsdl2-dev libboost-system-dev libboost-filesystem-dev libboost-date-time-dev libboost-locale-dev libfreeimage-dev libfreetype6-dev libeigen3-dev libcurl4-openssl-dev libasound2-dev libgl1-mesa-dev build-essential cmake git

Download the latest source

git clone https://github.com/Aloshi/EmulationStation

Compile and install it

cd EmulationStation
git checkout unstable
cmake .
make
sudo make install

sudo apt-get update

sudo apt-get install git dialog

cd
git clone --depth=0 https://github.com/petrockblog/RetroPie-Setup

chmod +x retropie_setup.sh
sudo ./retropie_setup.sh

sudo apt-get update
sudo apt-get upgrade
sudo rpi-update

sudo nano /boot/config.txt
# add or replace "gpu_mem = 32"
# if you skip this step, you will probably get "out of memory" errors when compiling

sudo reboot

sudo apt-get install -y libudev-dev libasound2-dev libdbus-1-dev libraspberrypi0 libraspberrypi-bin libraspberrypi-dev

sudo apt-get install -y libboost-system-dev libboost-filesystem-dev libboost-date-time-dev libboost-locale-dev libfreeimage-dev libfreetype6-dev libeigen3-dev libcurl4-openssl-dev libasound2-dev cmake g++-4.7

wget http://libsdl.org/release/SDL2-2.0.1.tar.gz
tar xvfz SDL2-2.0.1.tar.gz
rm SDL2-2.0.1.tar.gz
pushd SDL2-2.0.1
# "--disable-video-opengl" is used to disable the software implementation of desktop OpenGL on the Pi
# "--host=*" is used to force the Raspberry Pi host. See issue #395 on GitHub for details on why.
./configure --disable-video-opengl --host=arm-raspberry-linux-gnueabihf
make
sudo make install
popd

rm -rf SDL2-2.0.1

git clone https://github.com/Aloshi/EmulationStation
cd EmulationStation
git checkout unstable
# On the RPi 2, you may need to add '-DFREETYPE_INCLUDE_DIRS=/usr/include/freetype2/' before the period.
# See issue #384 on GitHub for details.
cmake -DCMAKE_CXX_COMPILER=g++-4.7 .
make

sudo make install

./emulationstation

sudo nano /boot/config.txt
# change "gpu_mem = 32" to "gpu_mem = 128" or "gpu_mem = 256", depending on your Pi model
sudo reboot

Configuring EmulationStation

WARNING: Do not edit configuration files while EmulationStation is running. This has been known to cause strange side effects, like overwritten files and melting the polar ice caps.

If you are using a pre-configured distribution like RetroPie, you can probably skip this section.

You might want to read the README.md file as well as this document.

The .emulationstation Folder

EmulationStation stores all of its configuration files relative to some "home folder." Every EmulationStation configuration file goes in a .emulationstation folder inside of this "home folder."

I occasionally refer to this path as ~/.emulationstation . Just mentally replace the ~ with your platform's home folder.

Windows

On Windows, the "home folder" is set by the %HOMEPATH% environment variable. To see where that actually is, just type it into the Windows Explorer window and press enter:

So, the complete path to the .emulationstation folder is %HOMEPATH%\.emulationstation .

Linux

On Linx, this is equivalent to the $HOME environment variable. This is where your terminal and file browser should start.

So, the complete path to the .emulationstation folder is $HOME/.emulationstation .

NOTE: On Linux, files and folders that start with a . are "hidden folders," so the .emulationstation folder may not appear. If you are using the terminal, you can use ls -a to list all files in a directory, including hidden ones. If you are using a graphical interface, there should be an option to show hidden files and folders.

The es_systems.cfg File

This is the main configuration file for EmulationStation. It is located at ~/.emulationstation/es_systems.cfg . It is an XML document that defines a list of systems . A system contains the minimum information required to find your games and start them.

Here is an example, with comments:

<!-- This is the EmulationStation Systems configuration file. All systems must be contained within the <systemList> tag.-->
<systemList>

<!-- Here's an example system to get you started. -->
<system>

<!-- A short identifier for the system. Used in some folder structures and error messages. -->
<name>snes</name>

<!-- A "pretty" name, displayed in the menus and such. This tag is optional. -->
<fullname>Super Nintendo Entertainment System</fullname>

<!-- The path to the top-most folder to start searching for games in. If the first character is '~', it will be expanded to the home folder. All subdirectories will be included. You can use forward slashes for any platform and backslashes on Windows. -->
<path>~/roms/snes</path>

<!-- A list of extensions to search for, delimited by commas or spaces. You MUST include the period at the start of the extension! It's also case sensitive. -->
<extension>.smc .sfc .SMC .SFC</extension>

<!-- This is the shell command that is executed to run a game. A few special tags are replaced if found in a command, like %ROM%. This example would run the shell command "snesemulator /home/user/roms/snes/Super\ Mario\ World.sfc".
<command>snesemulator %ROM%</command>

<!-- The platform(s) to use when scraping (download box art and such). You can see the full list of accepted platforms below. Everything should be lowercase. This is only *only* used to give more accurate search results, so this tag is optional. You can use multiple platforms, delimited by commas or spaces.  For example: "genesis, megadrive". -->
<platform>snes</platform>

<!-- This is the theme to load from the current theme set. This tag is also optional; if not set, it will default to the value of <name>. It is recommended that you use a name from the "Recommended Theme Names" list below to make installing themes as painless as possible.-->
<theme>snes</theme>

</system>

</systemList>

Notice all <system> s are listed inside of one <systemList> tag.

If you want to add another system, just add it like so:

<systemList>
<system>
<!-- System 1 -->
</system>

<system>
<!-- System 2 -->
</system>

<!-- And so on... -->
</systemList>

Systems are displayed in the order they are defined.

NOTE: If a system does not have at least one game present (that matches the extension list), it will not be displayed.
If no systems have games present, you will get an "invalid configuration" error!

Recommended Theme Names

EmulationStation will not restrict the names you pick for themes. However, in the interest of keeping installing themes a simple drag-and-drop process for everyone's setup, please use one of the following as your system's theme name:

NOTE: These are case sensitive on Linux.

3do
amiga
amstradcpc
apple2
art
atari2600
atari5200
atari7800
atari800
atarijaguar
atarijaguarcd
atarist
atarifalcon
atarixe
c64
colecovision
amstradcpc
fba
gamegear
gb
gba
gbc
gc
intellivision
macintosh
mame
mastersystem
megadrive
n64
neogeo
nes
ngp
ngpc
pc
pcengine
ports
psx
scummvm
sega32x
segacd
snes
zmachine
zxspectrum

(if it's not here, you are free to make something up, since a theme probably doesn't exist for it yet)

Platform Names

This is the list of valid platforms you can in a <platform> tag. The platform is used when scraping to provide more accurate results. You can use more than one platform.

NOTE: These are case sensitive.

(if you suspect this is not up to date, check src/PlatformId.cpp )

Launch Commands

Launch commands depend on what emulator you want to use.

95% of the time, /path/to/emulator %ROM% or C:\path\to\emulator.exe "%ROM_RAW%" works.

If you're using MAME, /path/to/mame %BASENAME% should do the trick.

The following strings are replaced in your launch command:

• %ROM% - Replaced with the shell-escaped absolute path to the selected ROM. On Linux, most Bash special characters are escaped with a backslash. On Windows, the ROM path is automatically enclosed in quotes, which is equivalent to "%ROM_RAW%" (as of version 2.0.1).
• %BASENAME% - Replaced with the "base" name of the path to the selected ROM. For example, a path of "/foo/bar.rom", this tag would be "bar". This tag is useful for setting up MAME.
• %ROM_RAW% - Replaced with the unescaped, absolute path to the selected ROM. If your emulator is picky about paths or you are on Windows, you might want to use this instead of %ROM%, but enclosed in quotes. For example: higan "%ROM_RAW%" .

Installing Themes

If you used the Windows installer or Debian package, a set of default themes should already be installed (to ~/.emulationstation/themes on Windows and /etc/emulationstation/themes on Linux).

As long as you used a name from the list above, you only need to download and extract the theme set to ~/.emulationstation/themes . If the themes folder doesn't already exist, just create it.

After that, select the new theme set in MENU -> UI SETTINGS -> THEME SET , like so:

That's it!

There's no dedicated Themes page on the website yet, but the official theme can be downloaded here.