RetroArch (formerly SSNES) is an open-source, multi-platform frontend for the libretro API. It is designed to be fast, lightweight, and portable. Although not technically correct, its functionality with emulator-based Libretro cores makes it viewed as a multi-system emulator.
RetroArch is available for Windows, OS X, Linux, Android, iOS (jailbroken), BlackBerry 10, Raspberry Pi, OpenPandora, PlayStation 3, PSP, Xbox, Xbox 360, GameCube, and Wii. There are also preliminary 3DS ports, though most of them need a *New* 3DS if they are to work properly, a few of these requiring installation in the .cia format.
- RetroArch Stable Builds
- RetroArch Nightlies
- Windows RetroArch-Nightly-Installer
- Ubuntu PPAs: Stable, Nightly/Testing
- Arch Linux User Repositories: Stable, Testing, All, libretro-super
- RetroArch for Android on Play Store
- RetroArch for Android - F-Droid nightly build repository
- RetroArch for iOS - Cydia nightly build repository
- RetroArch for PS3 (CFW) and PS3 (DEX) v.220.127.116.11
- RetroArch for Xbox and Xbox 360 v.18.104.22.168
- RetroArch for BlackBerry 10
- Main article: libretro#Cores
- Consistency across multiple platforms, using the same UI structure and a fully featured command line interface.
- Gamepad controlled menu system with multiple styles available, such as XMB or Material UI.
- Gamepad auto-configuration profiles, so that gamepads are mapped automatically when connected. XInput controller autoconfig is built into the application, with other controller types available as external profiles.
- Per-core and per-game configuration overrides
- Custom resolution and refresh rate for video output, with exclusive fullscreen mode and monitor index for multi-monitor setups.
- Dynamic rate control for smooth audio and video, even when the game's output rate is different from your system. Especially obvious with systems like GBA that do not run 60Hz.
- Basic fast forward, SRAM saving, savestate, etc. It supports serialization of the emulation state which is used to provide real-time rewind and netplay.
- Pixel shaders, primarily using Cg and GLSL, with HLSL on Xbox 360. The shader format it uses is flexible and fairly easy to use, allowing for complex multi-pass effects with adjustable runtime parameters. Also supports traditional video filter plugins that are run in software.
- Supports audio DSP filter plugins through .dsp configuration files.
- Custom overlay support.
- FFmpeg recording and playback support. It can record either the native resolution output of the core or the post-processed output of the frontend. Playback is handled through an internal FFmpeg libretro core.
- GGPO-like netplay (latency hiding rollback). It should be lag-free if everyone involved emulates at full speed, doesn't live on opposite sides of the world and has decent internet speeds. It uses peer-to-peer UDP and supports two players. Due to rollback it requires a fair amount of CPU power to run, and the core must support serialization.
- Options for decreasing input latency related to vsync by eliminating buffering by the video driver, as well as using frame delay to delay polling of inputs until right before a vsync occurs on the display.
- Main article: Using RetroArch
Netplay is now usable from the menu in current builds, under Settings>Netplay Options. You can get it to work with the command line or the long-deprecated RetroArch-Phoenix Launcher as well in older builds.
You must specify whether you will be hosting (server) or joining (client) the game. If joining, you must also enter the host's IP address in the field below. Make sure your firewall is open on port 55435 (default; you can change it if you like) and that the port is forwarded in your router, if applicable. You can also specify 'spectator mode,' which will allow an arbitrary number of spectators to join and watch you play without being able to play themselves.
Delay frames denotes the maximum number of frames RetroArch will need to emulate at once to maintain synchronization due to actual network latency. You can figure out an appropriate ballpark for this number by pinging the other player and dividing the time (in milliseconds) by 16 (roughly the number of milliseconds in a frame from a game running at 60 fps). If the gameplay is a bit choppy, try increasing the number of delay frames a bit.
Similar to the GGPO platform, RetroArch creates a constant stream of savestates which, along with button presses, are exchanged and compared between the server and client machines. If the savestates start to diverge, the game rolls back in time to a point where they both agree and then emulates the missing frames all at once to get back to the appropriate spot. This gives the illusion of completely lagless inputs, which is invaluable for twitchy, fine controls.
If you try to connect to a server and it immediately says client disconnected, open your log and make sure your ROMs match exactly (it will complain about a hash mismatch otherwise). If it gives you a weird time-out error, just close the window and try to connect again and it should work itself out (sometimes excessive spikes in network latency can cause the states to diverge catastrophically, resulting in this error).
Alternative Launchers and Frontends
skeletonKey is the successor to retroInvader. In addition to a simple netplay interface, nearly every aspect of retroarch can be set using this GUI.
retroInvader is designed to allow users to quickly install & configure the latest version of RetroArch, cores, and shaders. In addition to the GUI-driven configuration & installation, retroInvader supports drag and drop for quickly launching ROMs, hosting netplay sessions as well as installing BIOS files. retroInvader is for Windows only.
RAEM (formerly RA-Player) is another launcher for RetroArch, for those that want to try something that looks more like a native Windows program. It hasn't been updated in a while, though.
Phoenix is an alternative frontend for libretro that is independent of RetroArch, not to be confused with the discontinued RetroArch-Phoenix launcher. It is intended to mimic the style of OpenEmu, except using libretro and being available on Windows and Linux. It is still in early development and requires that you build it yourself through Qt, though the main developer says an alpha release with prebuilt binaries is on the way.
Minir is another alternative libretro frontend that is independent of RetroArch and inspired by bsnes-Qt. It is stated to be a complement to RetroArch, focusing on things that RetroArch does not focus on, such as a system native GUI, cheat search, debugging, etc. This frontend is still in early development and no binary builds are provided yet, but you can build it yourself from the source code on Github.