Genecyst

Genecyst was a popular Sega Mega Drive/Genesis emulator for DOS, by Bloodlust Software (the same team that made NESticle). Due to its high speed and then-good YM2612 emulation (in version x.xx), it was widely regarded as the all-around best Mega Drive/Genesis emulator on the scene, with the nearest competitor being KGen. Genecyst has since been supplanted by newer emulators Gens and Kega Fusion.