EmuNations

Fceux is an open-source Nintendo Entertainment System and Family Computer Disk System emulator. It's a merger of various forks of FCE Ultra. While not being cycle-accurate, it's has quite an accurate emulation and offers extensive tools for debugging, rom-hacking...

Super ZSNES is a modern, from-scratch Super Nintendo emulator developed by the original ZSNES creators, built around a GPU-driven architecture rather than traditional CPU-focused. It emphasizes enhanced visuals, audio accuracy and a “Super Enhancement Engine”...

SameBoy is a user friendly Game Boy and Game Boy Color emulator that's very accurate and includes a wide range of powerful debugging features. In addition to accuracy and developer capabilities, it has features such as Battery save support, states save states, scaling filters...