DGen is a free, open source and portable emulator for Sega Genesis/Mega Drive systems. The latest version supports save states, interlace mode, Game Genie, Linux joystick support, compressed ROM images, and other nice features.
- Game Genie codes support
- PAL/NTSC, fullscreen modes
- Joypad / joystick support
- OpenGL textured video output
- Upscaling using hqx filters
- Low CPU usage on current hardware
- Portable (64-bit, endian-neutral)
- Screenshots, demos recording and playback
Maybe not the most accurate emulator, but open-source, compiles on Linux/x86-64, is still maintained, and has some great features (such as debugger or sprite boxing). It's great to see a Genesis emulator for Linux, even though it's limited to x86 and ARM architectures.