One other note: I tend to associate "x" with negative things UX/UI wise, so when I have a tile matched with it's respective zone color the "x" appearing within the tile to signal the bonus points kind of confused me. I think having an icon of some kind there is definitely helpful, but maybe a checkmark or plus sign instead.
Though come to think of it a "+" might also look like an "x" with the isometric view lol.