FCEUX is a cross platform, NTSC and PAL Famicom/NES emulator that is an
evolution of the original FCE Ultra emulator. Over time FCE Ultra had
separated into many separate branches.

The concept behind FCEUX is to merge elements from FCE Ultra, FCEU
rerecording, FCEUXD, FCEUXDSP, and FCEU-mm into a single branch of FCEU. As
the X implies, it is an all-encompassing FCEU emulator that gives the best
of all worlds for the casual player, the ROM-hacking community, Lua
Scripters, and the Tool-Assisted Speedrun Community.