Games like Close the Sky
Games like Close the Sky include Broken Arrow, Wargame: Red Dragon, WARNO, Men of War: Assault Squad 2, and Starship Troopers: Terran Command. We matched them by the tags players give Close the Sky on Steam (RTS, Strategy, Real Time Tactics, Tower Defense, and Wargame): closest matches first, and among equally close ones the better-known games.

Broken Arrow
Shared: Strategy · RTS · Wargame

Wargame: Red Dragon
Shared: RTS · Strategy · Wargame

WARNO
Shared: RTS · Real Time Tactics · Wargame

Men of War: Assault Squad 2
Shared: Strategy · RTS · Simulation

Starship Troopers: Terran Command
Shared: RTS · Strategy · Military

Stronghold Crusader HD (2012)
Shared: Real Time Tactics · Military · Strategy

Total War: THREE KINGDOMS
Shared: Strategy · RTS · War

Age of Empires III: Definitive Edition
Shared: Strategy · RTS · Base Building

Company of Heroes 2
Shared: Strategy · RTS · War

Wargame: Airland Battle
Shared: RTS · Strategy · Real Time Tactics

Creeper World 4
Shared: Real Time Tactics · Tower Defense · RTS

Syrian Warfare
Shared: RTS · Real Time Tactics · Wargame

Manor Lords
Shared: Strategy · Simulation · Base Building

Stronghold Crusader: Definitive Edition
Shared: Strategy · Real Time Tactics · Tower Defense

Hearts of Iron IV
Shared: Strategy · War · Military

Stronghold: Definitive Edition
Shared: Strategy · Real Time Tactics · RTS

Steel Division: Normandy 44
Shared: Strategy · RTS · Simulation

Planetary Annihilation: TITANS
Shared: RTS · Strategy · Real Time Tactics

Kingdom Heroes 8
Shared: RTS · Real Time Tactics · Strategy

Steel Division 2
Shared: RTS · Strategy · Military

Ultimate General: Civil War
Shared: Real Time Tactics · Wargame · RTS

Call to Arms - Gates of Hell: Ostfront
Shared: Strategy · Real Time Tactics · RTS

Call to Arms
Shared: Strategy · RTS · Military

Master of Command
Shared: Strategy · RTS · Real Time Tactics