Games like Frontier Protocol
Games like Frontier Protocol include BALL x PIT, RimWorld, Your Only Move Is HUSTLE, Prison Architect, and Door Kickers. We matched them by the tags players give Frontier Protocol on Steam (Immersive Sim, Strategy, Top-Down Shooter, Real Time Tactics, and Roguelite): closest matches first, and among equally close ones the better-known games.

BALL x PIT
Shared: Roguelite · Action · Top-Down Shooter

RimWorld
Shared: Strategy · Colony Sim · Base Building

Your Only Move Is HUSTLE
Shared: Strategy · 2D Fighter · Action

Prison Architect
Shared: Strategy · Colony Sim · Simulation

Door Kickers
Shared: Strategy · Action · Top-Down

Oxygen Not Included
Shared: Colony Sim · Strategy · Base Building

Cult of the Lamb
Shared: Roguelite · Colony Sim · Base Building

Door Kickers 2: Task Force North
Shared: Real Time Tactics · Strategy · Action

The Escapists
Shared: Strategy · Action · 2D

Heat Signature
Shared: Strategy · Action · Top-Down

Police Stories
Shared: Strategy · Action · Top-Down Shooter

Against the Storm
Shared: Strategy · Colony Sim · Base Building

Vampire Survivors
Shared: Roguelite · 2D · Action

Deep Rock Galactic: Survivor
Shared: Roguelite · Top-Down Shooter · Action

Going Medieval
Shared: Strategy · Colony Sim · Base Building

Dwarf Fortress
Shared: Strategy · Colony Sim · Base Building

Escape From Duckov
Shared: Top-Down Shooter · Action · Adventure

Drill Core
Shared: Strategy · Roguelite · Colony Sim

Stronghold Crusader: Definitive Edition
Shared: Strategy · Real Time Tactics · Colony Sim

Halo: Spartan Assault
Shared: Top-Down Shooter · Action · Strategy

UFO 50
Shared: Strategy · Action · Arcade

Rogue Legacy 2
Shared: Roguelite · Arcade · Action

Infection Free Zone
Shared: Strategy · Base Building · Colony Sim

Cluckmech Oasis
Shared: Strategy · Top-Down Shooter · Roguelite