TuxNES is an emulator for the 8-bit Nintendo Entertainment System. TuxNES is based on Nestra, a public-domain NES emulator by Quor. TuxNES adds many features not found in Nestra, and uses a more collaborative development model. Enhancements to Nestra often find their way into TuxNES. Enhancements to TuxNES don't generally find their way into Nestra due to licensing restrictions (since pieces of TuxNES are generally copyrighted by their authors, and covered by the GNU General Public License,) although similar changes by the same authors sometimes find their way back into Nestra. The program is under active development, with some features not yet implemented.