Fceux

FCE Ultra X [FCEUX] is an emulator of the original (8-bit) Nintendo Entertainment System (NES) released under the GNU General Public License (GPL). It includes the following features (and many more):

* fully customizable color palette rendering engine * complete sound emulation (all five channels) * support for up to four joystick controllers * zapper emulation for the mouse * GameGenie emulation * accepts compressed (PKZIP, gzip) ROM images * TCP/IP network play * Lua scripting