Brainix is a microkernel-based, Unix-like operating system. It includes support for virtual memory, preemptive multitasking, asynchronous message passing, and the ext2 file system. It was written from scratch and runs on IA-32 (x86) computers.
Brainix was inspired by (but shares no code with) Minix.
Brainix boots, initializes its sub-systems, then passes messages. It isn't mature enough to support a shell, but its developers are active.