Cepheus Protocol

Cepheus Protocol

Early access since May 2020

Cepheus Protocol is an Open World RTS Military Survival Game. Play as the CERC hunting Patient 0, maintain Quarantine camps, fight dangerous mutations & Rogue Civilian Combatants . There’s nobody else coming, it’s up to you now.

77% positive · 3,781 reviews
Not yet
In early access, content still planned
High confidence
Content Planned
Not yet
In early access, content still planned
High confidence
Content Planned

Where to buy

Steam $19.99
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Evaluation

Cepheus Protocol has been in Early Access since May 15, 2020 and remains under very active development as of October 6, 2026. The developer, Halcyon Winds, completed a major engine rebuild in early 2026 — switching the rebuilt version to the default install on January 7, 2026 — and has been systematically restoring and expanding gameplay systems on top of that new foundation throughout the year. The pace of development remains intense and highly public. The developer runs a weekly development livestream called CERC HQ (which reached its 100th episode in late July 2026), publishes detailed patch notes to Steam multiple times per month, and the most recent developer communication is dated September 4, 2026 — just over a month ago. Major systems shipped during 2026 include: the Doctrines progression tree (January 31, 2026), the Civilian Evacuation system (playable end-to-end as of May 2026), the CERC Ops live tactical companion app (July 27, 2026), Structure Blueprints and Squad Presets (August 13, 2026), a major Minimap overhaul (August 21, 2026), and a significant Tactical Map expansion with Replay System improvements (September 4, 2026). Content explicitly named as still in development includes: new infected variants, Lieutenants (infected late-game progression leaders), the Leviathan (a late-game super unit), Escalation systems, and the San Francisco North map expansion — all referenced in the May 24, 2026 roadmap post and not yet confirmed as shipped in subsequent updates. The September 4, 2026 patch notes also note continued active work on Tactical Map unit displays and Fog of War, describing these as ongoing areas of development. A 1.0 release has not been announced or dated. The game remains unfinished by the developer's own account, with significant gameplay systems still being built out.
Evidence
Tactical Map expansion and Replay System improvements shipped; patch notes reference continued work on Tactical Map unit displays and information panels as still in progress.
news post · Sep 4, 2026 source development ongoing
high
Structure Blueprints and Squad Presets systems launched as major new features, along with expanded Steam Workshop support.
news post · Aug 13, 2026 source content shipped
high

Content

7 of 7 released · no outstanding content

Media

Details

Developer
Publisher
Halcyon Winds
Achievements
5
Platform
Windows
Controller
partial support
Steam Deck
Playable
Players
Single-player · Multiplayer · Co-op

About this game

An Open World RTS Military Survival Game. Command CERC (Center for Epidemic Research and Control) to stop a pandemic-level event from consuming the Bay Area. The Pangu Virus threatens humanity as it spreads, turning native inhabitants into infected, relentless swarms. Can you adapt, survive, and reclaim control?

Hardcore RTS Military Combat Meets Survival Horror

  • Aircraft Carrier Operations
    Your mobile base of operations in Pandemic Mode. If it’s destroyed, you lose. Defend it at all costs and utilize Winters, now a rebuildable hero, to lead your forces.

  • A New Threat Rises
    Battle infected hordes that can infect and turn your own units. Command land, sea, and air forces to hold the line in this unforgiving world.

  • Co-Op Multiplayer up to 16 players in true RTS/TPS hybrid combat!
    Share control of CERC operations with up to 16 players. Pool resources, coordinate tactics, and fight as a team against the infection.

Dynamic Gameplay Systems

  • Command the Operator
    Control the battlefield in Third-Person Shooter mode or use the Operator as a hero unit in RTS mode. Adapt your strategies to survive.

  • Doctrine Tree Progression
    Unlock new support options, powerful weapons, and unique units by leveling up through the Doctrine tree.

  • Customize Pandemic Mode
    Create your perfect challenge. Turn off infected types, adjust gameplay options, and create custom scenarios to tailor the experience.

  • Character Progression
    Improve your characters’ health and targeting efficiency as they gain experience through combat.

Innovative Mechanics and Features

  • Line of Sight and Hearing AI
    Experience cutting-edge AI that hunts your units based on what they can see and hear. Stay stealthy, or face overwhelming swarms.

  • Massive, Detailed Maps
    Explore sprawling urban environments filled with varied locales. Plan every attack, defense, and civilian evacuation carefully to ensure survival.

  • Dynamic Civilian Diplomacy  (Legacy Only Coming in Q2 to rebuild)
    Interact with rogue civilian groups. Recruit them to your cause, negotiate alliances, or defend yourself from hostile factions.

  • Civilian Evacuation (Legacy Only Coming in March to rebuild)
    Manage who lives and dies with an intricate Civilian Administration Structure. Customize your intake system or use preset templates to make critical decisions.

Destroy the Infection

  • Research the Pangu Virus
    Delve into the secrets of the alien pathogen and find a way to kill Patient 0 before it’s too late.

  • Hunt Patient 0 and Their Lieutenants
    Stop the infection from spreading by targeting its leaders. Destroy their expanding hordes before they consume every province.

  • Dynamic Provincial Events
    Encounter unexpected challenges as rogue civilian combatants and infected groups form dynamically across the map. Your reputation and decisions will shape the world around you.

  • Enhanced Operator Customization
    Tailor weapons, abilities, and appearance. Drive vehicles, gain progression perks, and refine your playstyle for maximum impact.

Planned Features

  • DNA Research System
    Develop a proper progression tree to counter the virus, protect your units, and evolve your strategies.

  • Canon Campaign Mode
    Experience the official Cepheus Protocol story, inspired by the novel and side stories

Last evaluated Oct 6, 2026
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