The Rebuild Is Now the Main Game (Build Switch Update)
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The Rebuild is now the standard installed version of Cepheus Protocol.
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The old version is now called Legacy, and it remains available as a Beta option.
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This rebuild was done to restore stability, improve performance, and modernize the foundation so the game can scale again.
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That same foundation also allows co-op to exist from the start, instead of being bolted on later.
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We are targeting end of Q1 2026 to bring back the remaining missing pillars, rebuilt and improved.
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Default (Standard Install)
This is now the rebuilt version of Cepheus Protocol and the main version we maintain going forward. Play this for the current supported game, best performance, and all new updates. -
Experimental (Beta Branch)
This is the testing branch ahead of Default, where upcoming features land first. Expect bugs, frequent updates, and possible save issues. Opt-in only if you want to help test new changes early. -
Legacy (Original) (Beta Branch)
This is the preserved prebuild version for older saves and the original gameplay foundation. Opt into this if you want to continue old saves or stay on the classic build. This branch will not receive future updates. You can see the “foundation” that we based the rebuild on for the newly merged into “default” here. -
Legacy (Pre Merge) (Beta Branch)
This is the last version from before the rebuild became Default. If you were playing the rebuild while it was still a Beta branch.
Going forward, when you install Cepheus Protocol, you are installing the rebuilt version.
For most of the last year, the rebuilt version existed as an opt in Beta branch while we validated the foundation in public tests. A lot of players never saw that Beta branch, which caused real confusion about what version was being worked on and why certain things felt inconsistent.
So we are ending that confusion. The game is alive as ever and is still passionately worked on a daily basis by our team. We have been biding our time developing the rebuild on public/private betas slowly ticking away at the core mechanics missed from the rebuild readding them as we go. We now feel the current state of the game is enough to flip the builds.
Going into next week we will be shipping Doctrines and start the save system. We expect to have an early doctrines to show by Friday and have it in UI wise by mid next week. We will update as we progress here and on our discord.
https://steamcommunity.com/games/979640/announcements/detail/537736957039477253https://steamcommunity.com/games/979640/announcements/detail/537735054151909378A few notable changes recently:
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Infected Military, Police and Swat will now roam the island with higher stats then standard infected. They start showing up early and increase in numbers as the days go on!



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Infantry Gates

New Infected Variants replace legacy models
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16 Player Coop RTS/TPS hybrid gameplay!
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Firing Computer from the MLRS ported to the Cerberus Mortar with the rebuild
Legacy remains available as a preserved snapshot of the pre rebuild version.
If you want to keep playing that older snapshot, or if you want to keep older saves, you can do that through Steam Betas.
This was not a content patch. It was a full foundation revamp.
We rebuilt the core systems so the game can scale properly again, run better, and stop breaking under the weight of legacy technical debt. That benefits everything:
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Single player flow and stability
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AI behavior and consistency
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Vehicle systems and reliability
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Large scale performance
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Future content velocity
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Co-op support as a first class feature
Co-op is not the point of the rebuild. Co-op is one of the benefits of doing the rebuild correctly.
We currently have two Horde experiences built in the rebuilt framework:
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Half Moon Bay (Horde Rush)
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Forward progression style Horde
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Push the map and keep momentum instead of only holding ground
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RTS Coop Test (Horde)
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Traditional horde map experience
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Operators were built in lockstep with the rebuilt foundation, not as a disconnected system.
Current Operator baseline includes:
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Weapon customization (early version)
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Attribute points
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Appearance baseline
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Gunsmith/Operator UI is not final and will be improvement over the next few weeks as Winters mockups up a new design
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True RTS/TPS Hero Units you can customize
Operators will expand significantly as we move into Doctrines, including:
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Driving vehicles
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Operating turrets
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Using new and ported abilities such as laser designation for support actions when we add in the ability to call in airstrikes and support options!
Pandemic is now the next major phase, built on the foundation validated through Horde.
Currently playable areas include:
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Calypso
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Half Moon Bay
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Treasure Island Open World Slice
Additional areas planned but currently locked:
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Angel Island
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San Francisco North
These areas will unlock later once missing enemy roster and mode pillars are complete.
Here is the consolidated list, in one place, so there is no confusion.
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January Goals
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Remaining Vehicle Abilities And Behaviors
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Bradley TOW
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Merlin vehicle transport
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Save System for Pandemic
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Doctrines
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BUGS, BUGS and Bugs! We still are hunting down desyncs and bugs as they are reported!
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February Goals
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Remaining Enemy Roster Needed For Angel to be unlocked
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Leviathan
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Birds
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Additional Pandemic Regions Locked Until The Above Is Complete
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Angel Island
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San Francisco North
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TBD
We are committed to not rushing to the “end” to ensure everything prior is working correctly. These are the ones currently in limbo that we will be tackling once the above list is “completely” done.
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LHA6 & LCAC
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Civilian Evacuation
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Dynamic Civilian Groups
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That is the remaining gap we are closing through Q1. Anything else will be discussed only after the current list above is done.
Our target through Q1 2026 is to bring back the remaining missing pillars and have the rebuilt version fully represent the complete Cepheus Protocol experience again, but better.
That means:
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More stability and performance
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Larger scale gameplay
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More and better maps
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Complete Pandemic mode pillars
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Operators expanding toward Doctrines
This build switch is about clarity.
From now on:
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The installed version of the game is the rebuilt version
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Legacy remains available as a preserved snapshot
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The rebuild is what we maintain and grow from here
If you want to help shape it, the biggest thing you can do is:
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Play the current build
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Give feedback on what feels good and what feels broken
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Report bugs and edge cases
Thank you for sticking with us through this rebuild period. The foundation is finally where it needs to be, and now we are building the rest of Cepheus Protocol on top of it.