Keep the jewels. Delete the baggage.
Zygaena is a desktop-focused operating system built on Hammerhead, its base system. Hammerhead began as a fork of illumos, the open-source continuation of Solaris, and has diverged deliberately since.
Most operating-system projects describe what they added. The clearest way to describe this one is what it removed — and the removals are specific and countable. What is left is a base system small enough for one person to hold in their head.
What the project is trying to do
Keep what made Solaris worth keeping
ZFS, DTrace, zones, and process contracts, as the real implementations inherited through illumos — not reimplementations and not partial ports. This is the whole reason to start from illumos rather than from nothing.
Delete what held it back
SMF and its XML manifests. IPS and a Python package manager in the base system. SPARC and 32-bit multilib. NIS, LDAP and the dead name services. Roughly sixty-six legacy drivers. The Sun-descended build tools. Every deletion costs compatibility, and that trade is made on purpose.
Be modern from the compiler up
GCC 14, GNU Make, GNU ld for userland, Meson and Ninja in the ports tree. /usr/lib, not /usr/lib/amd64. Self-hosting since March 2026: Hammerhead compiles Hammerhead, on Hammerhead.
Aim at the desktop
Not a server-only relic and not a museum piece. An X11 desktop runs today, over a virtual framebuffer, with Openbox above XLibre. The direction of travel is a curated catalog of genuinely useful software installed with Coral from the zports tree — a Unix workstation in the sense that phrase used to mean something.
- Not installable yet — zyginstall is in development.
- Not production software. Pre-alpha; don't put data on it you care about.
- Not binary-compatible with illumos or Solaris. The clean break is the point.
- Not broadly hardware-supported: amd64, UEFI, validated on KVM, no GPU acceleration.
- Not seeking upstream adoption — these are deletions illumos couldn't accept and shouldn't be asked to.
- Not a commercial offering. Leafscale stewards it; it is open source.
They are all marine, and deliberately so. Sphyrna zygaena is the smooth hammerhead; Isurus is the mako genus; coral and reef are the structures the rest is built on.
Upstream, and the neighbours
illumos is the parent and is credited everywhere. Tribblix showed that an illumos system does not need IPS, and the project says so in its own docs. OpenIndiana, OmniOS and SmartOS all aim at compatibility or production service; Zygaena trades both away for a smaller system. FreeBSD is the nearest cultural cousin — a coherent base system with a ports tree — on a different lineage.