Mega-Pi vs RetroArch

Mega-Pi is a free, bare-metal Sega Mega Drive/Genesis emulator for Raspberry Pi hardware. It targets Raspberry Pi 3 and 4 and runs without an operating system such as Linux, which the project associates with near-instant boot and very low input latency. The emulator uses the Picodrive core and Circle bare-metal C++ framework, assigning orchestration, video, audio, and input work across four ARM cores. It scans .bin, .md, and .gen Genesis or Mega Drive files, plus Sega CD/Mega CD .cue files with .bin tracks and compressed .chd files. Sega CD emulation includes the Sub-CPU, PCM audio, CD audio, and rotation/scaling graphics hardware. Video uses 2× integer nearest-neighbor scaling to 640×480, with 44.1 kHz stereo through the Pi PWM sound engine. USB gamepads and keyboards are supported, and save states reside on the SD card. Running it requires a FAT32 card, boot files, a kernel image, game files, and USB input devices; Sega CD also needs regional BIOS files.

RetroArch is a frontend for emulators, game engines, and media players, bringing them under a unified settings system. The RetroArch/Libretro project includes more than 200 cores across those categories. Its menu can group scanned games by system and display thumbnails and animated backgrounds. Common game controllers configure automatically when plugged in, and button actions can also be assigned manually.

Stackable shaders can change rendered graphics or imitate the look of CRT monitors. Built-in netplay supports hosting or joining network gaming sessions, including spectator mode. RetroArch can record gameplay to video files and stream games to Twitch or YouTube. Versions are listed for Windows, Linux, Android, iOS, macOS, and web browsers. RetroArch is free and open source under GPL version 3; the libretro API uses an MIT license. Features differ by platform and store version: the browser edition has lower performance and fewer capabilities than the full version, while Steam lacks Core Updater and thumbnail scraping and offers a selected core set.