Games like 3XTINCTION - Premium Pack 1
Games like 3XTINCTION - Premium Pack 1 include Left 4 Dead 2, The Last Stand: Aftermath, Splatter - Zombiecalypse Now, 12 is Better Than 6, and Deployment. We matched them by the tags players give 3XTINCTION - Premium Pack 1 on Steam (Action, Shooter, Zombies, Top-Down Shooter, and Twin Stick Shooter): closest matches first, and among equally close ones the better-known games.

Left 4 Dead 2
Shared: Zombies · Shooter · Action

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

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

12 is Better Than 6
Shared: Action · Shooter · Top-Down Shooter

Deployment
Shared: Shooter · Top-Down Shooter · Action

Left 4 Dead
Shared: Zombies · Action · Shooter

RUNNING WITH RIFLES
Shared: Action · Top-Down Shooter · Military

DayZ
Shared: Zombies · Shooter · Post-apocalyptic

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

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

HELLDIVERS™ Dive Harder Edition
Shared: Top-Down Shooter · Action · Twin Stick Shooter

Call of Duty®: Black Ops III
Shared: Zombies · Shooter · Action

Arma 3
Shared: Action · Shooter · Military

Killing Floor 2
Shared: Zombies · Shooter · Action

Pavlov
Shared: Shooter · Action · Zombies

Crimsonland
Shared: Action · Shooter · Top-Down Shooter

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

Halo: Spartan Assault
Shared: Action · Top-Down Shooter · Shooter

Strike Force Heroes
Shared: Action · Shooter · Arena Shooter

Nation Red
Shared: Action · Zombies · Top-Down Shooter

WARDOGS
Shared: Action · Shooter · Military

Counter-Strike: Source
Shared: Shooter · Action · Tactical

Yet Another Zombie Defense HD
Shared: Zombies · Top-Down Shooter · Shooter

Chippy
Shared: Twin Stick Shooter · Top-Down Shooter · Arena Shooter