Games like Service with a Shotgun
Games like Service with a Shotgun include Left 4 Dead 2, Metro Exodus, METRO Last Light Redux, S.T.A.L.K.E.R. 2: Heart of Chornobyl - Standard Edition, and METRO 2033 Redux. We matched them by the tags players give Service with a Shotgun on Steam (Pixel Graphics, Visual Novel, FPS, Text-Based, and Post-apocalyptic): closest matches first, and among equally close ones the better-known games.

Left 4 Dead 2
Shared: FPS · Zombies · First-Person

Metro Exodus
Shared: FPS · Post-apocalyptic · Singleplayer

METRO Last Light Redux
Shared: FPS · Post-apocalyptic · First-Person

S.T.A.L.K.E.R. 2: Heart of Chornobyl - Standard Edition
Shared: FPS · Post-apocalyptic · Singleplayer

METRO 2033 Redux
Shared: FPS · Post-apocalyptic · First-Person

Call of Duty®: Black Ops III
Shared: FPS · Zombies · First-Person

Left 4 Dead
Shared: FPS · Zombies · Post-apocalyptic

Resident Evil Requiem
Shared: Zombies · FPS · First-Person

Killing Floor 2
Shared: FPS · Zombies · Post-apocalyptic

DayZ
Shared: Zombies · Post-apocalyptic · FPS

Fallout: New Vegas
Shared: Post-apocalyptic · Singleplayer · First-Person

Fallout 4
Shared: Post-apocalyptic · Singleplayer · First-Person

Black Mesa
Shared: FPS · First-Person · Singleplayer

The Final Station
Shared: Pixel Graphics · Post-apocalyptic · Zombies

Half-Life 2
Shared: FPS · First-Person · Singleplayer

Warhammer 40,000: Boltgun
Shared: FPS · Pixel Graphics · First-Person

Call of Duty: World at War
Shared: FPS · Zombies · First-Person

S.T.A.L.K.E.R.: Shadow of Chernobyl
Shared: FPS · Post-apocalyptic · First-Person

Dying Light
Shared: Zombies · First-Person · FPS

Dead Bits
Shared: FPS · First-Person · Zombies

Metro 2033
Shared: FPS · Post-apocalyptic · Singleplayer

Resident Evil Village
Shared: First-Person · Zombies · Singleplayer

Summer Memories
Shared: Pixel Graphics · FPS · Visual Novel

Far Cry® New Dawn
Shared: FPS · Post-apocalyptic · First-Person