4. Sega Master System 1986
Once the NES had left Atari in the dust, Nintendo was in desperate need of a head-to-head rival. Sega answered the call, designing its Master System to not only compete with the NES, but pack graphics and processing power that would put it to shame. The Master System was more powerful, but lacked the fame Nintendo already enjoyed in America. Still, Nintendo was forced to watch as Sega gained a foothold in Europe and South America, setting the stage for an all-out fight in the next generation.