Games like Undeadly
Games like Undeadly include XCOM: Enemy Unknown, XCOM 2, This War of Mine, Mutant Year Zero: Road to Eden, and The Long Dark. We matched them by the tags players give Undeadly on Steam (Turn-Based Strategy, Zombies, Strategy, Survival, and Atmospheric): closest matches first, and among equally close ones the better-known games.

XCOM: Enemy Unknown
Shared: Turn-Based Strategy · Strategy · Tactical

XCOM 2
Shared: Strategy · Tactical · Turn-Based Tactics

This War of Mine
Shared: Survival · Strategy · Atmospheric

Mutant Year Zero: Road to Eden
Shared: Strategy · Post-apocalyptic · Tactical

The Long Dark
Shared: Survival · Atmospheric · Exploration

Project Zomboid
Shared: Zombies · Survival · Post-apocalyptic

Infection Free Zone
Shared: Zombies · Strategy · Post-apocalyptic

The Last Spell
Shared: Turn-Based Strategy · Strategy · Tactical

The Last Stand: Aftermath
Shared: Zombies · Survival · Post-apocalyptic

7 Days to Die
Shared: Zombies · Survival · Post-apocalyptic

Total War: WARHAMMER III
Shared: Turn-Based Strategy · Strategy · Tactical

They Are Billions
Shared: Strategy · Zombies · Survival

Dead State: Reanimated
Shared: Zombies · Survival · Strategy

DayZ
Shared: Zombies · Survival · Post-apocalyptic

Jagged Alliance 3
Shared: Strategy · Turn-Based Strategy · Tactical

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

Days Gone
Shared: Zombies · Survival · Post-apocalyptic

STAR WARS Zero Company™
Shared: Turn-Based Strategy · Strategy · Tactical

Plague Inc: Evolved
Shared: Strategy · Zombies · Tactical

XCOM®: Chimera Squad
Shared: Turn-Based Strategy · Strategy · Tactical

Terminus: Zombie Survivors
Shared: Zombies · Survival · Turn-Based Strategy

Wasteland 2: Director's Cut
Shared: Strategy · Post-apocalyptic · Tactical

Sid Meier’s Civilization® VI
Shared: Turn-Based Strategy · Strategy · Tactical

Total War: ROME II - Emperor Edition
Shared: Turn-Based Strategy · Strategy · Tactical