Games like Onion Force
Games like Onion Force include Orcs Must Die! 2, Mount & Blade II: Bannerlord, Mount & Blade: Warband, Sang-Froid - Tales of Werewolves, and Orcs Must Die!. We matched them by the tags players give Onion Force on Steam (Strategy, Action, Adventure, Indie, and RPG): closest matches first, and among equally close ones the better-known games.

Orcs Must Die! 2
Shared: Action · Strategy · Tower Defense

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

Mount & Blade: Warband
Shared: Strategy · RPG · Action

Sang-Froid - Tales of Werewolves
Shared: Strategy · Action · Indie

Orcs Must Die!
Shared: Action · Strategy · Tower Defense

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

Deathtrap
Shared: Action · Strategy · RPG

Plebby Quest: The Crusades
Shared: Strategy · Indie · RPG

Kingdom Rush 5: Alliance TD
Shared: Strategy · Tower Defense · Cartoony

Caster
Shared: Action · Adventure · Indie

Dungeon of the ENDLESS™
Shared: Strategy · Indie · Tower Defense

Sands of Salzaar
Shared: Strategy · RPG · Indie

SteamWorld Heist
Shared: Strategy · Action · Indie

Rock 'N' Roll Defense
Shared: Strategy · Action · Adventure

Han Xiongnu Wars
Shared: Strategy · Action · Adventure

Notes of Soul
Shared: Action · Adventure · Indie

UFO 50
Shared: Indie · Action · Strategy

Overdungeon
Shared: Strategy · Indie · RPG

The Dungeon Of Naheulbeuk: The Amulet Of Chaos
Shared: Adventure · RPG · Strategy

The Scroll of Taiwu : Beyond The Dome
Shared: RPG · Strategy · Indie

SMITE 2
Shared: Action · Strategy · Adventure

Space Pirates And Zombies 2
Shared: Strategy · Action · Indie

Bardbarian
Shared: Strategy · Indie · Action

Dead Age
Shared: Strategy · RPG · Adventure