microkernel, that's good. i know of redox, minix also use microkernel but did not 'take off'

Minix did certainly take off, at least for Intel.

Will be nice to see some status: what it can do ? Some example processes, (screenshots) ...

And some motivation and main goals.

Here you go: https://mirror.drewdevault.com/ares.pdf

Two registers for return value is interesting: https://ares-os.org/docs/helios/syscalls/