Games like SwordSpire
Games like SwordSpire include Kingdom Heroes 8, Creeper World 4, Kingdom Rush - Tower Defense, Bad North: Jotunn Edition, and Total War: WARHAMMER III. We matched them by the tags players give SwordSpire on Steam (Action, Strategy, RTS, Strategy RPG, and Tower Defense): closest matches first, and among equally close ones the better-known games.

Kingdom Heroes 8
Shared: RTS · Strategy · Strategy RPG

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

Kingdom Rush - Tower Defense
Shared: Strategy · Tower Defense · Action

Bad North: Jotunn Edition
Shared: Wargame · Tower Defense · Real Time Tactics

Total War: WARHAMMER III
Shared: Strategy · RTS · Real Time Tactics

WARNO
Shared: RTS · Strategy · Wargame

Total War: WARHAMMER II
Shared: Strategy · RTS · Action

Master of Command
Shared: Strategy · RTS · Strategy RPG

Wargame: Red Dragon
Shared: Strategy · RTS · Wargame

Company of Heroes 3
Shared: Strategy · RTS · Wargame

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

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

Total War: ROME REMASTERED
Shared: Strategy · Action · RTS

Mount & Blade II: Bannerlord
Shared: Strategy · Action · Medieval

Warpips
Shared: Strategy · RTS · Tower Defense

Broken Arrow
Shared: Strategy · RTS · Wargame

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

Infested Planet
Shared: Strategy · Action · RTS

Aliens: Dark Descent
Shared: Strategy · Action · RTS

Total War: WARHAMMER
Shared: Strategy · Strategy RPG · RTS

Taur
Shared: Strategy · Action · Tower Defense

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

Kingdom Rush Origins - Tower Defense
Shared: Strategy · Tower Defense · 2D

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