Games like Swarm Survivor
Games like Swarm Survivor include The Last Stand: Aftermath, Resident Evil Requiem, Left 4 Dead 2, Escape From Duckov, and Resident Evil 4 (2005). We matched them by the tags players give Swarm Survivor on Steam (Action, Shooter, Roguelite, Top-Down Shooter, and Survival Horror): closest matches first, and among equally close ones the better-known games.

The Last Stand: Aftermath
Shared: Top-Down Shooter · Roguelite · Shooter

Resident Evil Requiem
Shared: Action · Survival Horror · Zombies

Left 4 Dead 2
Shared: Shooter · Action · Zombies

Escape From Duckov
Shared: Action · Shooter · Top-Down Shooter

Resident Evil 4 (2005)
Shared: Action · Survival Horror · Zombies

DayZ
Shared: Shooter · Zombies · Post-apocalyptic

METRO 2033 Redux
Shared: Action · Post-apocalyptic · Shooter

Fallout 4
Shared: Post-apocalyptic · Shooter · Action

SYNTHETIK: Legion Rising
Shared: Roguelite · Action · Top-Down Shooter

Resident Evil 4
Shared: Action · Survival Horror · Zombies

REMNANT II®
Shared: Action · Shooter · Dark

METRO Last Light Redux
Shared: Action · Post-apocalyptic · Shooter

BALL x PIT
Shared: Action · Roguelite · Top-Down Shooter

The Ascent
Shared: Top-Down Shooter · Action · Shooter

Dying Light
Shared: Survival Horror · Zombies · Action

Zombieville USA 3D
Shared: Action · Shooter · Top-Down Shooter

BioShock Infinite
Shared: Action · Shooter · Adventure

The Last of Us™ Part I
Shared: Shooter · Post-apocalyptic · Zombies

Splatter - Zombiecalypse Now
Shared: Action · Top-Down Shooter · Zombies

The Walking Dead: Saints & Sinners
Shared: Action · Shooter · Zombies

Resident Evil 2
Shared: Survival Horror · Action · Zombies

Metro Exodus
Shared: Action · Post-apocalyptic · Shooter

Yet Another Zombie Survivors
Shared: Top-Down Shooter · Roguelite · Zombies

Killing Floor 2
Shared: Shooter · Zombies · Action