Mesen is a NES/Famicom emulator and NSF player. It is still a work in progress - some features are currently incomplete or may change in future versions.

Mesen Features:
* High Accuracy - A lot of effort has gone into making Mesen as accurate as possible
* Stand-alone - Put the Mesen application into any folder and run it from there
* Supports: Save States, Movie/Audio Recording, Screenshots, Cheat Codes
* Supported Mapper List (130+): 0 to 13, 15 to 19, 21 to 27, 32 to 34, 37, 38, 44, 45, 47, 49, 52, 57, 58, 60 to 62, 64 to 80, 82, 85 to 89, 91 to 95, 97, 99, 101, 107, 112, 113, 115, 118, 119, 137 to 141, 143 to 157, 159, 163, 164, 176, 180, 184, 185, 189, 191 to 195, 200 to 203, 205 to 207, 210, 218, 225 to 228, 230 to 232, 240 to 243, 246
* NES and Famicom (including Famicom Disk System) support. Also supports: NSF, NSFe, VS System
* Net Play - Play online with friends
* Automatic updates - Mesen is able to check for updates and automatically install new versions of itself.
* Built-in Debugger
* Other Features: 7z/zip archive support, numerous video filters (xBRZ, Scale2x, NTSC, etc.), sound recorder, sound effects, etc.



Mesen v0.9.8 Changelog:

New Features
Debugger: General improvements as well as new features/tools (and bug fixes.)
NSF: Allow rewinding during NSF file playback and fixed an initilization problem with VRC6 audio.
History Viewer: Added a few new features and options, including allowing it to be used with NSF files.
Video: Added support for 512-color palette files (for color bit emphasis.)
Input: Added options to configure the deadzone size for analog sticks and to hide the mouse cursor when using a zapper.
Dip switches: Dip switches can now be configured for all cartridges that use them (instead of being limited to VS System games.)

Bug Fixes
APU: Fixed frame counter bug that caused audio to sometimes be paced slightly incorrectly.
APU: Fixed DMC power on state to match hardware test results.
PPU: Prevent palette updates during horizontal blank when rendering is enabled (to match expected hardware behavior.)
Namco 163: Fixed problems with battery save data.
Bandai FCG: Added support for EEPROM save data.
MMC5: Fixed incorrect attribute data when using fill mode.
VRC7: Updated audio instrument values to match the values recently dumped from hardware.
AOROM: Fixed power on mirroring state.
Misc: Fixed minor bugs in a variety of mappers (including mappers 112, 176, 320 and UNROM512.)
http://www.mesen.ca