Notes about the FM2 file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The FM2 file type is primarily associated with 'FCEUX'.
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.