Games like Siegebreaker
Games like Siegebreaker include Emberward, Tower Dominion, Mindustry, Loop Hero, and Nordhold. We matched them by the tags players give Siegebreaker on Steam (Strategy, Tower Defense, Resource Management, Roguelite, and Deckbuilding): closest matches first, and among equally close ones the better-known games.

Emberward
Shared: Tower Defense · Strategy · Roguelite

Tower Dominion
Shared: Strategy · Tower Defense · Roguelite

Mindustry
Shared: Tower Defense · Resource Management · Strategy

Loop Hero
Shared: Roguelite · Deckbuilding · Resource Management

Nordhold
Shared: Strategy · Tower Defense · Roguelite

Age of Darkness: Final Stand
Shared: Tower Defense · Strategy · PvE

The King is Watching
Shared: Tower Defense · Strategy · Resource Management

Kingdom Two Crowns
Shared: Tower Defense · Strategy · Building

Heretic's Fork
Shared: Tower Defense · Strategy · Deckbuilding

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

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

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

Orcs Must Die! Deathtrap
Shared: Tower Defense · Roguelite · Strategy

Dungeon Warfare
Shared: Strategy · Tower Defense · Resource Management

Bloons TD 6
Shared: Strategy · Tower Defense · Singleplayer

Magic: The Gathering Arena
Shared: Strategy · Deckbuilding · Turn-Based Strategy

Balatro
Shared: Strategy · Deckbuilding · Roguelite

Kingdom Rush Origins - Tower Defense
Shared: Strategy · Tower Defense · Tactical

Luck be a Landlord
Shared: Strategy · Roguelite · Deckbuilding

GemCraft - Chasing Shadows
Shared: Strategy · Tower Defense · Top-Down

Sir, We Have an Orc Problem
Shared: Tower Defense · Roguelite · PvE

Plants vs. Zombies GOTY Edition
Shared: Tower Defense · Strategy · Singleplayer

Orcs Must Die! 3
Shared: Tower Defense · Strategy · PvE

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