Why can't I go here?

It's not connected. The line that looks like it connects to it is actually just underneath it connecting the two greens on either side.

As far as I remember the game has a limitation of a single node connecting to at most 4 nodes. If you have more than that things get buggy.

https://preview.redd.it/m4ne1pu9fbng1.jpeg?width=320&format=pjpg&auto=webp&s=63f07cc06729e5008cc6883d03f3c216cba64363

Nodes with 5 connections are actually bugged and only some of the connections are real

Your left green is connecting to the top right green. Just looks like it connects to the middle. Do the blue up top

https://preview.redd.it/u6lnfbtehbng1.jpeg?width=320&format=pjpg&auto=webp&s=6470fe77e5654c1fb9dcea4af8749782e130edf0

That’s why

You just reminded me of the horrible memories of coming across a node which was going across two more nodes into a completely different node in a straightish line while those connections were right atop of each other. It…It took me a while to notice it.

Clear the boss node, you’ll be able to get to it then. You gotta look at the curves of the lines, this happened to me a couple times before I realized what was happening.

The only nodes it is connected to are the 2 cleansed zones on the left and the area with the boss at the top.

This whole algorithm behind map generation has been buggy since day 1. At this point you just learn to ignore it or accept it and move on. I’ve definitely taken breaks to calm down when it happens to citadels.