FCEUX

FCEUX is an open source emulator for the 8-bit Nintendo Entertainment System console and its Japanese version called Super Famicom. With this emulator, you can play most of the titles from the NES catalog on any PC. Best of all, FCEUX also includes tons of advanced tools, so you're sure to get the most out of the emulation experience.

One of the most surprising things about FCEUX is the possibility to play with another user locally or online. Plus, you can record a video of the game or extract the audio in real time while you play. This, along with the included code debugger and a pulse modifier to change the speed of the game make this a fantastic tool for speedrunners.

The emulator is compatible with the following NES ROM formats: NES, NFS, FDS and UNF. However, it can also work with ROMs stored in ZIP files, RAR, and 7z. It also lets you save games and control system configurations, along with offering the typical post-processing image filters to make it look like you're playing on an old-school CRT monitor.

In short, FCEUX is one of the best options for playing the classics from the NES catalog, thanks to how easy it is to use and the fact that it offers tons of extra features for users who want more bang for the buck when it comes to emulation.