FCEUX is a free and open-source emulator for Nintendo Entertainment System (NES) and Famicom systems. It includes a variety of debugging tools and features, such as memory viewers, trace logs, and breakpoints, making it a powerful tool for reverse engineering and ROM hacking. FCEUX also s save states, cheat codes, and various video filters and enhancements, allowing s to customize their gameplay experience. Finally, it has a -friendly interface and is available for Windows, Mac, and Linux systems.