- Real Time Strategy (RTS)
- Simulator
- Strategy
- Adventure
Game
Cepheus Protocol
Find patient zero before an alien virus takes over San Francisco and the cepheus protocol is enacted. Command your squad, save civilians, and stop the Pangu virus. Kill patient zero and save the world.
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.
About Cepheus Protocol
- Released
- May 2020
- Developer
- Halcyon Winds
- Engine
- Unreal Engine 5
- Platforms
- PC (Microsoft Windows)
Where to get it
Release, studio and platform data from IGDB. Store links go to the sellers, not to us. We do not sell games and we do not host files.
Browse everything
Sorted, filterable and paged. Every link goes to the author’s own download.
From the developers
Official announcements, newest first. Posted on Steam.
- Community Announcements2026.8.4.1 + 4.2 Experimental and Normal Patch NotesTHE BAY AREA IS COLLAPSING. The virus is loose across the peninsula. Flashpoints are erupting across the region as entire districts fall into chaos and infected swarms push deeper into civilian zones. CERC forces are already in the field. Embedded military reporters and frontline operators are transmitting battlefield coverage directly from active operations. The images you are about to see wer...
- Community Announcements2026.7.31.3 Quality of Life Update Live + GPU Fog of War Tonight on ExperimentalTHE BAY AREA IS COLLAPSING. The virus is loose across the peninsula. Flashpoints are erupting across the region as entire districts fall into chaos and infected swarms push deeper into civilian zones. CERC forces are already in the field. Embedded military reporters and frontline operators are transmitting battlefield coverage directly from active operations. The images you are about to see wer...
- Community Announcements2026.7.27 CERC OPS Arrives on Experimental Plus Major FixesThe virus is loose across the Bay Area. Flashpoints are erupting across the peninsula as entire districts fall into chaos and infected swarms push deeper into civilian zones.CERC forces are already in the field.Embedded military reporters and frontline operators are transmitting battlefield coverage directly from active operations. The images you are about to see were captured during recent com...
- Community AnnouncementsWorld Reveal of CERC Ops This Saturday!A New Way to Monitor the Battlefield This Saturday, during the 100th episode of CERC HQ, we will hold the world reveal of CERC Ops, a new tactical companion built specifically for Cepheus Protocol. CERC Ops connects directly to an active game session and provides a live operational view of the battlefield on a phone, tablet, laptop, second monitor, or console browser. It is designed to give pla...
- Community AnnouncementsMassive Performance Gains and Smarter Fog of War Are ComingThe virus is loose across the Bay Area. Flashpoints are erupting across the peninsula as entire districts fall into chaos and infected swarms push deeper into civilian zones. CERC forces are already in the field. Embedded military reporters and frontline operators are transmitting battlefield coverage directly from active operations. The images above were captured during recent combat deploymen...
- Community Announcements2026.7.11 AI, Performance & Helicopter Systems Update on ExperimentalThe virus is loose across the Bay Area. Flashpoints are erupting across the peninsula as entire districts fall into chaos and infected swarms push deeper into civilian zones.CERC forces are already in the field.Embedded military reporters and frontline operators are transmitting battlefield coverage directly from active operations. The images you are about to see were captured during recent com...
- Mods indexed
- 106
- Versions
- 0
- Newest tracked
- none yet
- Most disruptive update
- No breakage data for this game
Most downloaded
Measured from the source's own counts, summed across every release.
- Vietnam War TracksYea you knew this tracklist was coming. I included some slower songs and probably missed a lot of ones, just testing out the modding tools. The mod is 330MBs and all MP3s If y'all want me to remove/add songs let me know also thumbs up the mod Tracklist: (not in order) Fortunate Son- Creedence Cle...12.1k downloads
- CERC Loudspeakers: Quarantine CheckpointA loudspeaker recording for use at CERC checkpoints consisting of instructions and warnings to civilians. Created to make player checkpoints feel a little more alive, I may add more lines later but for now it's about 1:30 of speaking with 5 seconds breaks between sections. Audio voiced and edited...8.6k downloads
- CERC Loudspeakers: Evacuation ZoneA loudspeaker recording for use at CERC evacuation zones consisting of instructions and warnings to civilians who are waiting to evacuate the area. Created to make your evacuation areas feel more alive, A total of 2 minutes and 15 seconds of audio. Audio voiced and edited by me, any feedback is w...7.9k downloads
- CERC Loudspeakers: HQ AnnouncementsA loudspeaker recording for use at CERC bases or your HQ consisting of various announcements and updates for CERC soldiers. Audio voiced and edited by me, any feedback is welcome.7.6k downloads
- CERC Loudspeakers: Civilian InstructionsA set of lines dedicated to giving instructions to all those civilians that CERC is in charge of handling. Consists of some basic advice for dealing with signs of infection, warnings not to attempt breaking the state quarantine and some other assorted instructions. Audio voiced and edited by me,...7.5k downloads
- CERC Loudspeakers: Red ZoneA set of lines making various announcements from inside a Red Zone, an area completely overwhelmed by the infection. Takes on a harsher tone than some of the others, setting the tone for an area beyond saving. Audio voiced and edited by me, any feedback is welcome.7.0k downloads
- CERC Loudspeakers: Rock RadioA fully voiced radio station with 14 tracks, dialogue between each song covering various topics from in game lore to MRE cooking tips. Roughly an hour of audio in total with a seamless loop to keep your troops entertained for hours of patrols, relaxation or background noise. Enjoy the silky smoot...4.9k downloads
- DOOM Eternal OSTNo one is surprised there is a mod to add this. Almost the entire DOOM Eternal OST, took some of the ambient songs out because they're boring. 196 MBs for the mod! used MP3s instead of WAVs so if there's a problem let me know. also thumbs up the mod Tracklist: A Slayer City BFG Division Blood Har...4.8k downloads
- Prototype Radio Chatter PackA collection of three radio files created using radio chatter from the video game File 1: Calm, mostly radio calls about searching areas, air patrols, dealing with quarantine breaches, no combat lines. File 2: Alert. combat callouts, air support requests and general combat dialogue but everything...4.3k downloads
- Cepheus Protocol Royalty Free Loud Speaker SamplesA few sample tracks to get the party started4.3k downloads
- Sabaton Great War AlbumThis is a playlist of Sabaton's Great War Album, including Christmas Truce as well4.0k downloads
- EAS MessageAdds a custom lore friendly Emergency Automated Message to blast from your speakers in game.3.7k downloads
- stalker bandit radioI just wanted to add music for myself, in the end I got acquainted with the workshop for the first time3.6k downloads
- Sabaton Art of War AlbumThis is a playlist of Sabaton's Art of War Album. This album includes: Ghost Divison The Art of War 40:1 Unbreakable Cliffs of Gallipoli Talvisota Panzerkampf Union The Price Of A Mile Firestorm I did not include Sun Tzu says, The Nature of Warfare, and A Secret.3.3k downloads
- Sabaton Primo Victoria AlbumThis is a playlist of Sabaton's Primo Victoria Album including thier cover of the beast by Twisted Sister3.2k downloads
- Black Ops 1 Zombies SoundtrackThe full Black Ops 1 Zombies Soundtrack. Playlist: - 115 - Abra Macabre - Abracadavre - Beauty Of Annihilation - Clockwork Squares - Coming Home - Damned - Death on the Dance Floor - Laughing Corpses - Lullaby of a Dead Man - Pareidolia - Raining Teddy Bears - Slasher - Slight Chance of Zombies -...2.9k downloads
- FAH Music PackHello, This Is Now Legacy'ed. I Now Have A Full Version. FAH Command Music The Ram Leak Was Fixed With The New Music Player Enjoy - TJ PS This Will Not Change As It Was Not Updated In 4 Years I Hate When People Change Stuff After Not Touching It.2.4k downloads
- The Vietnam Experience30 songs to make these limp dick fuck ups into real men MP3 files for your RAMs convience sir. First upload lets see how this goes song list: Aerosmith - Dream On Black Sabbath - War Pigs Booker T & the M G's - Green Onions Buffalo Springfield - For What i's Worth Creedence Clearwater - Bad Moon...1.7k downloads
- New Vagas RadioFallout NV radio. 16 songs in total MP3 files for your RAMs convenience sir. I was gonna do the others with time but I smashed them all out, enjoy the only 3 Bethesda fallout games released, their radio's anyway. I am thinking of doing a best of fallout and interlace it with 3 dog announcements b...1.7k downloads
- Mark's Community Bangers to Blast out of a Helicopter while Shooting Zombies!This mod is made for the sole purpose for the community to build its own playlist! these first songs were collected from the Cepheus Protocol discord along with some of my choices I will continue to add songs, anyone is welcome and encouraged to suggest songs, as long as they fit the theme of 'Ba...1.7k downloads
- USSR AnthemBlast those capitalists with our glorious music!1.6k downloads
- Prototype OSTI decided to port over the Prototype OST over to Cepheus Protocol for the speaker asset that is in game! Hopefully in more future updates there will be an option to replace the cepheus protocol in game soundtrack with the Prototype OST as well as replacing the main menu music with the Alex mercer...1.6k downloads
- Halo 3 OST"Wake me...When you need me." Halo 3 OST. no idea why I am on this grind but here I am. Song List: Halo 3 Behold a Pale Horse Halo 3 Black Tower Halo 3 Brutes Halo 3 Choose Wisely Halo 3 Dread Intrusion Halo 3 Edge Closer Halo 3 Farthets Outpost Halo 3 Finish the Fight Halo 3 Follow Our Brothers...1.5k downloads
- PAYDAY 2 Assault Soundtrack1.5k downloads
Browse all 106 Cepheus Protocol mods Sortable by downloads, rating and date.
More strategy games see all
Why Cepheus Protocol mods break
A mod is compiled against one version of a game. When the game updates, anything that reached into the parts that moved stops working, and it usually stops working silently rather than with a message that explains itself.
That is what the table above counts. It is not a guess: each row is a mod the community has reported as broken by that specific release. The number is a fair measure of how disruptive an update was, and it is the reason people delay updating a game they have modded heavily.
Common questions
Does IndexGG host Cepheus Protocol mods?
No, and it never will. Every download link points at the author's own page on Nexus, GitHub, CurseForge or wherever they published it. We index the ecosystem; the files stay with the people who made them.
Where does the compatibility data come from?
From the communities that maintain it in the open, not from guesswork. Each claim carries how it is known, so a reported breakage is never presented as though the author said it.
Why is a mod listed as broken when it works for me?
Compatibility depends on your exact game version and the rest of your load order. A mod marked as broken in one release may work fine on an older one, which is exactly why the version is recorded next to the claim rather than a bare yes or no.