Games like Operation: Outbreak
Games like Operation: Outbreak include Left 4 Dead 2, METRO 2033 Redux, Resident Evil Requiem, Resident Evil Village, and Resident Evil 7 Biohazard. We matched them by the tags players give Operation: Outbreak on Steam (Zombies, Horror, Survival Horror, Shooter, and FPS): closest matches first, and among equally close ones the better-known games.
Left 4 Dead 2
Shared: Zombies · FPS · Shooter
METRO 2033 Redux
Shared: Horror · FPS · Post-apocalyptic
Resident Evil Requiem
Shared: Zombies · Survival Horror · Horror
Resident Evil Village
Shared: Horror · Survival Horror · Zombies
Resident Evil 7 Biohazard
Shared: Horror · Survival Horror · Zombies
METRO Last Light Redux
Shared: FPS · Post-apocalyptic · Horror
Metro Exodus
Shared: FPS · Post-apocalyptic · Singleplayer
Dying Light
Shared: Zombies · Horror · Survival Horror
Killing Floor 2
Shared: Zombies · FPS · Horror
Resident Evil 2
Shared: Zombies · Horror · Survival Horror
DOOM
Shared: FPS · Shooter · Action
Back 4 Blood
Shared: Zombies · FPS · Shooter
Left 4 Dead
Shared: Zombies · Horror · FPS
Call of Duty®: Black Ops III
Shared: Zombies · Shooter · FPS
Resident Evil 4
Shared: Horror · Survival Horror · Zombies
Call of Duty®
Shared: FPS · Shooter · Singleplayer
Ready or Not
Shared: Shooter · FPS · Horror
Resident Evil 4 (2005)
Shared: Survival Horror · Zombies · Horror
Half-Life: Alyx
Shared: Horror · FPS · Shooter
Black Mesa
Shared: FPS · Shooter · Action
The Last of Us™ Part I
Shared: Horror · Zombies · Post-apocalyptic
DayZ
Shared: Zombies · Shooter · Post-apocalyptic
Killing Floor
Shared: Zombies · FPS · Horror
Outlast
Shared: Horror · Survival Horror · First-Person