NES Emulator

RetroArch

RetroArch is a multi-system emulator that can play NES games plus hundreds of other systems (SNES, Genesis, Game Boy, etc.). It's highly customizable with shader filters, save states, and controller mapping. The downside is it has a steeper learning curve and a less intuitive interface compared to the others. It's the most feature-rich if you want to emulate multiple systems, but overkill if you just want NES.

Nestopia

Nestopia is NES-focused and known for accuracy—it emulates the NES hardware very closely, which matters if you care about authentic behavior and compatibility with obscure games. It's lightweight, simple, and straightforward to use. The interface is clean and no-nonsense. It's a solid choice if you just want reliable NES emulation without extra features.

FCEUX

FCEUX (an evolution of the older Famicon Emulator) is also NES-focused and highly accurate. It's been around forever and has a dedicated community. It includes built-in tools for ROM hacking, debugging, and frame-by-frame analysis. The interface looks dated, but it's very stable and reliable. Good if you want power-user features alongside accuracy.

Recommendation

For streaming NES games: I'd recommend Nestopia or FCEUX. Both are lightweight, accurate, and won't eat your system resources. Nestopia is simpler and cleaner if you just want to hit play and stream. FCEUX has more advanced features if you tinker. RetroArch is overkill unless you plan to stream multiple retro systems.