Download

Pre-alpha

Castalia GOS has no public installable release yet — the honest state of the project lives in the roadmap. When the public alpha ships, this page will offer signed ISOs with checksums and cosign signatures for the AMD/Intel edition and the two NVIDIA editions (open kernel modules for RTX 50, closed for RTX 40 and older).

Build it yourself, today

The image already builds and boots. With podman, just, and ~40 GB free:

git clone https://github.com/Tombatossals-Softworks-LLC/CastaliaGOS.git
cd CastaliaGOS
just build            # build the OCI image from the Bazzite base
just run-container-test
just build-iso qcow2  # ready-to-boot VM disk → output/qcow2/disk.qcow2

Full walkthrough, VM setup, and the in-VM verification checklist: Build & Test guide.

The manual

Nine guides cover installing, first boot, updating and rolling back, Steam, controllers, NVIDIA, anti-cheat, and the ROM/BIOS legal position — written against the shipped code, not against the design docs.

Install — verify, write a USB, run Anaconda, reach first boot
First boot — the twelve Castalia Portal steps, and what each changes
Update & rollback — why a bad update cannot brick the machine
Troubleshooting — the symptom index everything else links back to
Steam · Controller · NVIDIA
Anti-cheat — read before buying a competitive shooter
ROM & BIOS legality — what emulation here does and does not include

Verify what you run

ISOs ship with SHA-256 checksums — that is the check to run, and the one that works today.

Published images are cosign-signed, by digest, with the project's real key — the committed cosign.pub is that key, so you can verify any image yourself. What is not switched on is on-machine enforcement: the machine does not check the signature for you on update yet, because a verification policy that is wrong about the registry or the key path stops the update channel working, and that has not been proven across a real upgrade cycle. The Update & rollback guide spells out exactly what is and is not guaranteed.