Case: Blockade

When we have a clue of $2$, and skyscraper $N$ is at the back of that lane, then we know skyscraper $N-1$ must lie immediately in front of that clue.

The $N-1$ blocks all skyscrapers behind it except the tallest one. If it weren’t at the front, we’d be able to see more in front of it, leaving at least 3 skyscrapers in view.

[!Tip] This is reminiscent of Singularity.

This deduction only applies if $N$ is at the very end of the lane. If it’s not, then $N-1$ could be hiding behind it. In that case we’d have Haven.

However, notice that if the cell(s) behind the $N$ can’t contain $N-1$, then the only place for the $N-1$ to go is at the front of the lane.

It’s like this the lane has shrunk such that $N$ is effectively at the back.

So overall, if $N-1$ can go behind $N$ then anything could happen. But if it can’t hide, then it must be directly in front of the $2$ clue.