I sent a PR that was supposed to close the Part 1 of Z-level update. BevapDin reviewed and merged it. Then I made a claim for the bounty.
Kevin didn’t comment yet and also didn’t accept or reject the claim for the bounty.
First part was purely technical. I’m working on the second part, which is mostly about changing everything to use 3D points and at the very end making monsters, items and vehicles outside current z-level do stuff.
It won’t be until Part 3 when you can look up and see birds flying above your head, though.