The ReactOS project is a ground-up implementation of a Microsoft Windows XP/2003 compatible operating system. ReactOS aims to achieve complete binary compatibility with both applications and device drivers meant for NT and XP operating systems, by using a similar architecture and providing a complete and equivalent public interface.
A special-purpose 4.4BSD-based UNIX-like operating system, designed for machine control applications. Using low-cost hardware, FabBSD can be used to control a wide array of CNC milling machines, lathes, routers, process-control and automation equipment.
Phantom: Persistent Operating System
Applications in Phantom OS do not have to stop when OS stops. Even abrupt reboot does not lead to loosing application state.
Detailed description: https://phantomdox.readthedocs.io/en/latest/