Concept is solid, I enjoyed exploring it at the beginning. But the balance is off -- rebirths are pretty samey, just to get a little bit of lunarity. When I started my fourth rebirth I realized how slow everything was going and that the hidden unlocks were all speed-related upgrades that would take quite a lot of playtime to get to, so I lost interest.
I'm curious about the two remaining locked tabs, but I don't think I'll get to them.