3run is right, the lines mark the positions where logical "units" (basically "rooms") are connected to each other. Sometimes, you can only move to the next area there, other times, the entire edge shared by those rooms are passable. You know, mixing things up
We have thought about adding such a faction control system, and it's still something we'd like to implement, but we expect that it might still take a while until there are enough players for both factions to be well-balanced for such a direct conflict to be fun. Until then, we stick with an indirect version of it, which is easier to balance without feeling cheesy.
Perhaps this post will get me points for originality at least.
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