Puzzle #50 - Lattice 2.0 (Regional Skyscrapers)

This Regional Skyscrapers puzzle was my entry for Logic Showcase #5, in which constructors had to make a Geisterbahn. What's a Geisterbahn? A puzzle type with about 20 rules that the constructor chooses which ones apply. I saw "all numbers in a region must be the same" and "all numbers in a region must be different" and knew I wanted my puzzle to use both. Skyscrapers seemed a natural extension to that.

In addition to normal Skyscrapers rules, each region contains exactly one number. This puzzle uses the set {1, 2, 3, 4}.

puzz.link interface       penpa interface

This puzzle was the organizer of the showcase's favorite puzzle, even though it placed... 6th of 9, I think?