Games like Slimeball Castle Wars
Games like Slimeball Castle Wars include Age of Empires II (Retired), Bloons TD 6, Age of Empires: Definitive Edition, Age of Empires III: Definitive Edition, and Stronghold: Definitive Edition. We matched them by the tags players give Slimeball Castle Wars on Steam (Strategy, City Builder, RTS, Tower Defense, and 2D): closest matches first, and among equally close ones the better-known games.

Age of Empires II (Retired)
Shared: Strategy · RTS · Medieval

Bloons TD 6
Shared: Strategy · Tower Defense · Multiplayer

Age of Empires: Definitive Edition
Shared: Strategy · RTS · City Builder

Age of Empires III: Definitive Edition
Shared: Strategy · RTS · City Builder

Stronghold: Definitive Edition
Shared: Strategy · City Builder · RTS

Stronghold Crusader: Definitive Edition
Shared: Strategy · City Builder · Medieval

Plants vs. Zombies GOTY Edition
Shared: Strategy · Tower Defense · 2D

Anno 1800
Shared: Strategy · City Builder · RTS

Stronghold Crusader 2
Shared: Strategy · City Builder · RTS

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

Sid Meier’s Civilization® VI
Shared: Strategy · Multiplayer · City Builder

Mindustry
Shared: Tower Defense · Strategy · RTS

Kingdom Two Crowns
Shared: City Builder · Tower Defense · Strategy

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

Thronefall
Shared: Strategy · City Builder · Tower Defense

Ancestors Legacy
Shared: Strategy · RTS · Medieval

Stronghold HD (2012)
Shared: City Builder · Medieval · Tower Defense

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

ShellShock Live
Shared: Strategy · 2D · Multiplayer

A Total War Saga: THRONES OF BRITANNIA
Shared: Strategy · RTS · Medieval

Knights of Honor II: Sovereign
Shared: Strategy · RTS · Medieval

Cossacks 3
Shared: Strategy · RTS · Multiplayer

Kingdoms Reborn
Shared: City Builder · Strategy · Multiplayer

They Are Billions
Shared: Strategy · RTS · City Builder