Obi's new tiles with a less distinct outline would be the bomb.

Also, what SE said about rain.



EDIT: I thought about the theme a bit - how did this Roman-era city become a ruin? - with disastrous results:



I turned snow into something that might resemble volcanic ash. I think it makes the green details pop out more and meshes better with the blue background, but it's only a suggestion. No idea how to include the ice into the theme, unless we're willing to accept that a nuclear winter took place...