Alien Syndrome

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Alien Syndrome
Arcade flyer
Developer(s)	Sega Sanritsu (NES, Master System)
Publisher(s)	Sega
Composer(s)	Tohru Nakabayashi (arcade) David Whittaker (computers) Noboru Machida (NES)
Platform(s)	Arcade, Amiga, Atari ST, Commodore 64, Game Gear, MS-DOS, MSX, NES, Master System, ZX Spectrum, X68000
Release	1987: Arcade, Master System 1988: Amiga, Atari ST, C64, Famicom, MSX, NES 1989: Spectrum, MS-DOS 1992: Game Gear, X68000
Genre(s)	Run and gun, horror
Mode(s)	Single-player, multiplayer
Arcade system	Sega Pre System 16, Sega System 16B

Alien Syndrome (エイリアンシンドローム, Eirian Shindorōmu) is a run and gun video game developed by Sega and released in arcades in 1987, and later ported to the Master System the same year. The game utilizes a side-scrolling feature that allows the player to take control of either a male (Ricky) or female (Mary) soldier whilst hunting aliens and saving hostages before they run out of time.

Alien Syndrome released with a strong opening, becoming one of Sega's best-selling video games for the Master System. It received generally positive reviews, with praise towards the gameplay, character designs, sounds, and horror theme. It was included as a bonus game in the Genesis compilation game, Sonic's Ultimate Genesis Collection (2009). A sequel of the same name was released in 2007 to a strong negative response from critics.