81		Heat Signature (Windows, 2017)
65		If It Moves, Shoot It! (DOS, 1989)
65		Blasteroids (DOS, 1989)
65		Space Snake (DOS, 1989)
65		Zappa Roidz (DOS, 1989)
65		Hellraider (DOS, 1989)
65		Xenon (DOS, 1989)
64		Space Miner (DOS, 1990)
64		Jackson City (DOS, 1990)
64		Giant Space Slug (DOS, 1990)
64		Time Bandit (DOS, 1988)
64		Speed Zone (DOS, 1988)
64		Galactic Battle (DOS, 1990)
64		Star Dust (DOS, 1988)
64		Bedlam (DOS, 1988)
63		X-Fire (DOS, 1991)
63		Slordax: The Unknown Enemy (DOS, 1991)
63		Cogmind (Windows, 2017)
63		Starsiege: Tribes (Windows, 1998)
62		Mutant Storm (Windows, 2003)
62		Tunnel Divers (Windows, 2017)
62		Crimsonland (Windows, 2003)
62		Assault Android Cactus (Windows, 2015)
62		Ikaruga (Windows, 2014)
62		Waves (Windows, 2011)
62		Geometry Wars 3: Dimensions - Evolved (Windows, 2014)
62		Everyday Shooter (Windows, 2008)
62		Teleglitch (Windows, 2012)
62		Alien Swarm: Reactive Drop (Windows, 2017)
62		Mr. Smoozles Goes Nutso (Windows, 2006)
62		Starfire (DOS, 1992)
62		Ricochet Infinity (Windows, 2007)
62		Kiloblaster (DOS, 1992)
61		Xenon 2000: Project PCF (Windows, 2000)
61		Mirage Thunder (DOS, 1993)
61		Solar Winds: Galaxy (DOS, 1993)
61		Neon Chrome (Windows, 2016)
61		Jim Power: The Lost Dimension in 3D (DOS, 1993)
61		Alien Stars (Windows, 2008)
61		ROX (DOS, 1993)
61		Waves 2 (Windows, 2015)
61		Major Stryker (DOS, 1993)
61		Blacksea Odyssey (Windows, 2016)
61		SubSpace (Windows, 1997)
61		Raiden IV: OverKill (Windows, 2015)
61		Geometry Wars: Retro Evolved (Windows, 2007)
61		Solar Winds: The Escape (DOS, 1993)
61		Earth Invasion (DOS, 1993)
60		SYNSO: Squid Harder! (Windows, 2009)
60		Gum Drop: Celestial Frontier (Windows, 2009)
60		Pawarumi (Windows, 2018)
60		Astro Tripper (Windows, 2009)
60		Bullet Candy Perfect (Windows, 2009)
60		Biodrone Battle (Windows, 2015)
60		Beat Hazard (Windows, 2010)
60		Robotz DX (Windows, 2010)
60		TerraFire (DOS, 1997)
60		Razor2: Hidden Skies (Windows, 2010)
60		SYNSO:CE (Windows, 2010)
60		Squid Yes! Not So Octopus! (Windows, 2009)
60		Urban Uprising: Dark New World (Windows, 2006)
60		Vortex (Windows, 2015)
60		Marsh (Windows, 2010)
60		Starcom (DOS, 1997)
60		Space Strike (Windows, 2007)
60		Chicken Invaders: Revenge of the Yolk (Windows, 2006)
60		Astro Fury (Windows, 2008)
60		Angelfish (Windows, 2006)
60		Clash'N Slash: Worlds Away (Windows, 2006)
60		Fuck Space! (Windows, 2006)
60		Space Renegades: The Series (Windows, 2006)
60		Mars Miner (Windows, 2007)
60		Star Defender 4 (Windows, 2007)
60		Uriel's Chasm (Windows, 2014)
60		Scavenger (Windows, 2007)
60		Bullet Candy (Windows, 2006)
60		Raiden III (Windows, 2006)
60		Space Shot (Windows, 2008)
60		Droid Assault (Windows, 2008)
60		Star Sword (Windows, 2008)
60		Alien Assault (Windows, 2008)
60		Protoganda II (Windows, 2008)
60		Debrysis (Windows, 2008)
60		xWUNG (Windows, 2007)
60		Polybius (Windows, 2007)
60		Varia (Windows, 2007)
60		Protoganda: Strings (Windows, 2007)
60		1337 Ship Deathmatch (Windows, 2009)
60		X-Orbtek II (Windows, 2013)
60		Kiloblaster 3 (DOS, 1994)
60		Total Carnage (DOS, 1994)
60		The Orion Project (DOS, 1994)
60		Galaga 94 (DOS, 1994)
60		Traffic Department 2192 (DOS, 1994)
60		Laser Cycle (DOS, 1983)
60		XO-Fighter (DOS, 1982)
60		It came from space, and ate our brains (Windows, 2015)
60		Tachyon Project (Windows, 2015)
60		Pixel Space_ (Windows, 2015)
60		Shoot 1UP (Windows, 2015)
60		Kiloblaster 1 (DOS, 1994)
60		Kiloblaster 2 (DOS, 1994)
60		Day of Pigs (DOS, 1996)
60		SPIN (DOS, 1996)
60		Out 'M' Up (DOS, 2000)
60		Rocks (DOS, 1997)
60		SplayMaster (DOS, 1996)
60		Blast-off (Windows, 2017)
60		Star Hammer (DOS, 1994)
60		Return of the Mutant Space Bats of Doom (DOS, 1995)
60		Override (Windows, 2017)
60		Threat (DOS, 1995)
60		Swarm Universe (Windows, 2017)
60		Blockships (Windows, 2016)
60		Inferno+ (Windows, 2012)
60		Uriel's Chasm 2: Et (Windows, 2015)
60		Caverns of Mimas (Windows, 2012)
60		Miner Wars Arena (Windows, 2012)
60		Miner Wars 2081 (Windows, 2012)
60		Robot King Part I: Rebooted and Ready (Windows, 2017)
60		Raiden IV (Windows, 2015)
60		JASEM: Just Another Shooter with Electronic Music (Windows, 2017)
60		Ion Assault (Windows, 2010)
60		Invaders: Corruption (Windows, 2010)
60		Orbit (Windows, 2015)
60		Blast (Windows, 2017)
60		Axia (DOS, 1998)
60		Super Killer Hornet: Resurrection (Windows, 2014)
60		Project Root (Windows, 2014)
60		Crimzon Clover: World Ignition (Windows, 2014)
60		Broken Pearl (Windows, 2014)
60		Major Stryker (Windows, 2014)
60		Velocity: Ultra (Windows, 2013)
60		Verminian Trap (Windows, 2013)
60		Solar Flux (Windows, 2013)
60		Battle Squadron (Windows, 2013)
60		Guardic (Windows, 2016)
60		Rage Against the Machine (DOS, 1997)
60		Scrap Galaxy (Windows, 2017)
60		Nighthaw-X3000 (Windows, 2017)
60		When Clones Attack! (Windows, 2002)
60		Chicken Invaders: The Next Wave (Windows, 2002)
60		Project GunViper (Windows, 2002)
60		Chicken Invaders (Windows, 2002)
60		Crusaders of Space 2 (Windows, 2007)
60		Outbreak (Windows, 2001)
60		Cho Ren Sha 68k (Windows, 2001)
60		Cunyngas (Windows, 2003)
60		Final Impact (DOS, 1998)
60		Warblade (Windows, 2003)
60		Fobos (Windows, 2003)
60		Hail to the Chief (Windows, 2004)
60		Angriff vom Saturn (Windows, 2003)
60		Crimzon Clover (Windows, 2010)
60		Deimos Rising (Windows, 2003)
60		Arcadia (Windows, 2010)
60		RayStorm (Windows, 2001)
60		Startron (Windows, 2000)
60		Battle-Girl (Windows, 1998)
60		Tyrian 2000 (DOS, 1999)
60		Chase Ace (Windows, 1998)
60		Final Impact (Windows, 1998)
60		Scud: Industrial Evolution (Windows, 1997)
60		Space Rocks 3D (Windows, 1996)
60		Take No Prisoners (Windows, 1997)
60		Destruction Carnival (Windows, 1997)
60		Galactic Patrol (Windows, 1998)
60		Chase Ace 2 (Windows, 1999)
60		Bugatron (Windows, 2000)
60		Space Haste (Windows, 2000)
60		Space Rescue (Windows, 2000)
60		Tyrian 2000 (Windows, 1999)
60		Star Havoc (Windows, 1999)
60		Infantry (Windows, 1999)
60		Metaloids (Windows, 1999)
60		Mutant Storm: Reloaded (Windows, 2012)
60		Protector (Windows, 2001)
60		Ultratron (Windows, 2005)
60		UwiTron (Windows, 2005)
60		Communist Mutants From Space (Windows, 2005)
60		Alien Breed Obliteration (Windows, 2005)
60		ArkLight (Windows, 2005)
60		Alienoid (Windows, 2004)
60		Mutant Mahem (Windows, 2004)
60		Pteroglider (Windows, 2004)
60		(Not) Just another Space Shooter (Windows, 2004)
60		Crusaders of Space (Windows, 2006)
60		Panic Invaders (Windows, 2004)
60		Star Defender II (Windows, 2005)
60		Hero (Windows, 2005)
60		Jewel of Orion (Windows, 2005)
60		Alien Outbreak 2: Invasion (Windows, 2007)
60		Clash'N Slash (Windows, 2005)
55		Stargoose Warrior (DOS, 1989)
55		Obliterator (DOS, 1989)
55		Meteors (DOS, 1989)
55		Ajax (DOS, 1989)
55		Moonwalker (DOS, 1989)
54		Mad Show (DOS, 1988)
54		Better Dead Than Alien! (DOS, 1988)
54		Xenon 2: Megablast (DOS, 1990)
54		Unreal (Windows, 1998)
54		Bomberman (DOS, 1992)
54		Arkanoid (DOS, 1988)
54		Unreal Tournament (Windows, 1999)
54		Dunjax (DOS, 1990)

Notes: Games similar to Alien Syndrome, Games like Alien Syndrome, SEGA Enterprises Ltd., SEGA Enterprises Ltd., DOS, Action, Sci-Fi, Futuristic, Arcade, Shooter, Top-down, Space station, Spaceship, PC, Game Similarities.