Alien Storm

Alien Storm (エイリアンストーム) is a 1990 beat 'em up/shooter arcade game by Sega. It was later ported to the Sega Mega Drive/Genesis and Sega Master System. The Sega Mega Drive version was also released on Wii's Virtual Console in 2007. The game appeared in Sega Mega Drive Ultimate Collection for Xbox 360 and PlayStation 3.

Technical Note:

Alien Storm ran on the "System 18" platform, which was an updated version of "System 16" that adhered to the JAMMA standard and could be more easily installed in generic arcade cabinets. System 18 had an additional sound chip and two more tile layers than System 16, but was otherwise nearly identical, utilizing the same CPU, resolution, and colors.

There was a bootleg version of Alien Storm that was very common in the United States that was distinguishable in that the player characters had different color palettes. That version was never fully emulated and after the ROM was dumped over 26 years ago, it is not clear that anyone kept the bootleg PCBs.