Cepheus Protocol
Halcyon Winds · released May 15, 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.
Price
$19.99
US store
Reviews
76%
3,038 · Mostly Positive
Playing now
51
sampled 14h ago
24h peak
51
all-time seen 64
Followers
22,253
23h ago
Owners (est.)
~91.1K
45.6K – 146K
YouTube activity
6
videos · 30 d17
creators469K
views · 1 yTwitch activity
—
avg viewers · 30 d—
hours watched · 30 d—
streamers · 30 dProduct info
from Steam's PICS · read 3d ago- Change number
- 40,757,134
- Public build
- 24,829,887 · Aug 20, 2026 (2mo ago)
- Operating systems
- windows
- Architecture
- 64-bit
- Install size
- 12 GB · 11 GB download
- Install folder
Cepheus Protocol- Controller support
- Partial
- Metacritic
- —
- Homepage
- cepheusprotocol.com/
- Release state
- released
- Community
- hub · Workshop · stats
Steam Deck
PlayableTested Sep 25, 2026 on build 24,829,887
- !Default controller config not fully functional
- !Text input does not automatically invokes keyboard
- !Interface text is not legible
- !Default configuration is not performant
- ✓Default controller config fully functional
- ✓Controller glyphs match deck device
Branches · 4
every build Steam serves for this app| Branch | Build | Updated | Description |
|---|---|---|---|
| public | 24,829,887 | Aug 20, 2026 · 2mo ago | |
| experimental | 26,505,136 | Nov 7, 2026 · 6d ago | Preview build with new features. Unstable, frequent updates, saves may break. |
| legacy | 20,415,865 | Jan 7, 2026 · 10mo ago | The branch before we merged the rebuilt game as default on 1.6.25 |
| legacy-premerge | 15,464,740 | Aug 31, 2025 · 1y ago | Build from before experimental was merged into the live branch. |
Build history
every build id we have seen on a branch (history starts with our first read)| Build | Branch | Released | First seen |
|---|---|---|---|
| 26,505,136 | experimental | Nov 7, 2026 11:53 | 3d ago |
| 24,829,887 | public | Aug 20, 2026 04:25 | 3d ago |
| 20,415,865 | legacy | Jan 7, 2026 03:05 | 3d ago |
| 15,464,740 | legacy-premerge | Aug 31, 2025 20:55 | 3d ago |
Depots · 10
content of the public branch| Depot | Name | OS | Language | DLC / shared | Size | Download | Manifest |
|---|---|---|---|---|---|---|---|
| 979641 | windows 64-bit | 12 GB | 11 GB | 8190979047784837192 | |||
| 1387390 | all | DLC Cepheus Protocol Novelization | 1.1 MB | 913 KB | 1286529532299846223 | ||
| 1997150 | all | DLC Cepheus Protocol Digital Art Book | 12 MB | 11 MB | 2646314920170677226 | ||
| 2496500 | windows 64-bit | DLC Cepheus Protocol - Support Pack Vehicle Camo Classic Wars Collection | 1.2 MB | 1.2 MB | 7113364543456853873 | ||
| 2496510 | windows 64-bit | DLC Cepheus Protocol - Support Pack Vehicle Camo Modern Collection | 775 KB | 770 KB | 8725575257045246761 | ||
| 2496520 | all | DLC Cepheus Protocol - Support Pack Vehicle Camo NATO Collection | 127 KB | 108 KB | 3007699981174887082 | ||
| 2514440 | windows 64-bit | DLC Cepheus Protocol - Free Vehicle Camo Post Modern Collection | 11 KB | 3.3 KB | 5343426092076636058 | ||
| 2540710 | all | DLC Cepheus Protocol - The Last Line Novella | 501 KB | 438 KB | 7374174257502697085 | ||
| 228989 | windows | shared from #228980 | — | — | |||
| 228990 | windows | shared from #228980 | — | — |
Launch options · 4
| Executable | OS | Description |
|---|---|---|
CepheusProtocol.exe |
windows 64-bit beta: legacy,legacy-premerge | Default |
CepheusLauncher.App.exe |
windows 64-bit | Launcher |
CepheusProtocol.exe |
windows 64-bit | Without Launcher |
CepheusProtocol\Mods\ModUploader.exe |
windows 64-bit | Upload Workshop Mod |
Languages · 9
| Language | Interface | Full audio | Subtitles |
|---|---|---|---|
| French | ✓ | — | — |
| German | ✓ | — | — |
| English | ✓ | ✓ | — |
| Korean | ✓ | — | — |
| Russian | ✓ | — | — |
| Spanish | ✓ | — | — |
| Japanese | ✓ | — | — |
| Simplified Chinese | ✓ | — | — |
| Portuguese | ✓ | — | — |
Packages · 1
all packages| Sub | Name | Billing | Price |
|---|---|---|---|
| 322111 | Cepheus Protocol | Store or CD key | $19.99 |
Bundles · 2
all bundles| Bundle | Games | Bundle discount | Price |
|---|---|---|---|
| Cepheus Protocol Origins Edition | 2 | -10% | $35.05 |
| Upgrade to "Supporter Edition" | 1 | -5% | $28.46 |
DLC in product info · 7
includes DLC not sold separatelyCepheus Protocol NovelizationCepheus Protocol Digital Art BookCepheus Protocol - Support Pack Vehicle Camo Classic Wars CollectionCepheus Protocol - Support Pack Vehicle Camo Modern CollectionCepheus Protocol - Support Pack Vehicle Camo NATO CollectionCepheus Protocol - Free Vehicle Camo Post Modern CollectionCepheus Protocol - The Last Line Novella
Updates · patch notes
Steam announcements tagged as patch notes, linked to the public build they followed
No patch notes seen yet for this game.