Mesen is a free and open-source Famicom (NES), Famicom Disk System (FDS), Super Famicom (SNES), GB/GBC and PC-Engine/TurboGrafx-16 emulator for Windows, Linux and macOS. The version currently under development is Mesen 2.x, first released as a preview build in 2023. The older Mesen 0.x branch could only emulate NES, and SNES/GB(C) emulation was found in a separate emulator named Mesen S. The current Mesen Libretro core for RetroArch is still based on the 0.x branch, but receiving backports from the newer branch. Features: According to test ROMs, it is ranked as the most compatible NES/FDS emulator, slightly above puNES with a score of 100%. It has cycle-accurate emulation and offers numerous features, including: Support for over 290 mappers, (all licensed games supported.) FDS (Famicom Disk System) support Top loader NES variant support VS. System support Dendy support HDNes HD packs NTSC/PAL support NSF/NSFe support Video recording/playback Video filters (xBRZ, NTSC, etc.) Netplay Debugging tools Overclocking Custom palettes Sound effects (fake stereo, reverb, etc.) Rewind Mesen 2.x can also run SNES games, which also feature similar features, as well as Super FX and Satellaview support. Game Boy (DMG) and Game Boy Color (CGB) games can also be played on Mesen 2.x, but only Game Boy Color can play CGB games. For DMG games, you can choose either Game Boy or Game Boy Color, or run the game in Super Game Boy mode by loading the Super Game Boy BIOS (1 or 2) into the SNES core. An exclusive feature excluded from older versions is PC-Engine support, as well as the CD-ROM.