Great idea, superb art.
I get the aesthetic, but I wish the towers and fragments were more identifiable. I have kind of a hard time looking at a tower and discerning what it does after I've placed it 5 minutes ago. I think the 4 elements should be even further identifiable related to their respective abilities, other than the color coding.
It would be cool if you could also grapple along the pillars along the map.