Apart from a focus on shooting lots of enemies, this genre scrolls on a fixed axis, either automatically (like Xevious) or by player input (like Defender).
Hybris
Amiga 1987@2
Menace
Amiga 1988@1685
Battle Squadron
Amiga 1989@3
Twin Hawk
Arcade 1989@1778
Vimana
Arcade 1991@1779
Dogyuun
Arcade 1992@1462
Batsugun
Arcade 1993@1446
Mahou Daisakusen
Arcade 1993@1447
Gunbird
Arcade 1994@1003
Twin Cobra II
Arcade 1996@995
Armed Police Batrider
Arcade 1998@1127
Espgaluda
Arcade 2003@1456
Carrier Air Wing
CP System 1990@2611
19XX: The War Against Destiny
CP System II 1995@2824
Dimahoo
CP System II 2000@2838
GG Aleste
Game Gear 1990@2892
Life Force
NES 1987@1454
Gun-Nac
NES 1990@1922
Crisis Force
NES 1991@1363
R-Type I
PC Engine 1988@2573
W Ring: The Double Rings
PC Engine 1990@2625
Sylphia
PC Engine CD 1993@3238
G-Darius
PlayStation 1998@1407
R-Type Final
PlayStation 2 2003@42
Raiden III
PlayStation 2 2005@1619
Dariusburst Chronicle Saviours
PlayStation 4 2015@1633
Hyper Sentinel
PlayStation 4 2018@2029
R-Type Final 2
PlayStation 4 2021@2795
1943: The Battle of Midway
PlayStation 4 2021@3336
Truxton
SEGA Genesis 1989@1451
Flight of Pigarus
SEGA Master System 2018@3285
Super R-Type
SNES 1991@231
Raiden Trad
SNES 1992@1796
R-Type III: The Third Lightning
SNES 1993@181
Scramble
Scramble, March 1981@987
1993 Space Machine
Steam Deck 2022@3324
Solace
Windows 2010@203
Jamestown
Windows 2011@332
Deathsmiles: Deluxe Edition
Xbox 360 2007@272
Guwange
Xbox 360 2010@354
Sine Mora
Xbox 360 2012@431