69		Burn the Trash! (Windows, 2007)
63		Demons to Diamonds (Windows, 2010)
63		Centipede (Windows, 2010)
63		Spider Fighter (Windows, 2010)
61		Galaxy Invaders (Windows, 2004)
61		Millipede (Windows, 2004)
60		Bit-Bat (DOS, 1982)
60		Choppy the Pork Chop (Windows, 1996)
60		Älg Invaders: Return of the Gädda (Windows, 2016)
60		Centipede (DOS, 1983)
60		Buggers (Windows, 2001)
60		Tick Attack (DOS, 1983)
58		The Ultra Mission (Windows, 2010)
55		Galaxian (Windows, 2008)
54		Invaders Possibly from Space (Windows, 2009)
54		Totally Tiny Arcade (Windows, 2007)
54		Back to Earth 2 (Windows, 2007)
54		Fractal Fighter (Windows, 2007)
53		Space Armada (Windows, 2010)
53		Astrosmash (Windows, 2010)
53		Titan Attacks! (Windows, 2006)
52		Love Invaders (Windows, 2005)
51		Galaga (Windows, 2004)
51		Back to Earth (Windows, 2004)
51		Alien Sky (Windows, 2004)
50		Clone Invader (DOS, 1989)
50		Bandits! (DOS, 1992)
50		Worm Burner (DOS, 1987)
50		Zapshot (DOS, 1986)
50		The Interceptor (DOS, 1993)
50		Cash Invaders (DOS, 2002)
50		CHAMP Invaders (DOS, 1997)
50		Spac3 Invaders Extr3me (Windows, 2018)
50		PC-Fun (DOS, 1985)
50		TIE Invaders (DOS, 1996)
50		Super Stupid Space Invaders (DOS, 1997)
50		Avenger (DOS, 1997)
50		Space Commanders (DOS, 1983)
50		1979: Invasion Earth (Windows, 2017)
50		Space Invaders (DOS, 1995)
50		CHAMP Galaxia (DOS, 1996)
50		Alien Attack (DOS, 1993)
50		Fighter (Windows, 1995)
50		FreeStrike (Windows, 2001)
50		3105 A.D. (Windows, 2003)
50		Space Invaders (Windows, 1999)
50		Invaders 95 (Windows, 1995)
50		Just Shoot The Thing! (Windows, 2000)
50		Orbsters (Windows, 1997)
50		LaserAge (Windows, 1999)
50		Xoldiers (Windows, 2008)
50		Super Destronaut (Windows, 2016)
43		Megamania (Windows, 2010)
43		Asteroids (Windows, 2010)
40		Shooting Stars! (Windows, 2016)
40		ET's Turbo Pig Bash (Windows, 1999)
40		Crazy Hunt (Windows, 2008)
40		Space Commanders II (DOS, 1985)
40		AstroRaid (Windows, 2003)
40		Prügel Star: Lande den Volltreffer! (Windows, 2003)
40		PenG (Windows, 2001)
40		Mud Hunt (Windows, 2000)
40		Captain vs Sky Pirates (Windows, 2017)

Notes: Games similar to RETRO 4, Games like RETRO 4, Cactus Software, Cactus Software, Windows, Action, Shooter, Fixed, Flip-screen, Game Maker, Fixed-screen shoot 'em up, PC, Game Similarities.