improved visual clarity

These things come immediately to mind:

peg drawing – Either we should draw the pegs as css circles, like we now do on the modal peg placement popup (as opposed to the .png being used now), or make the .png look more like a peg somehow. It might be worth experimenting with css shadows to see how that looks.
selected states on pieces – Ideally this would be a highlight around the piece image, rather than a square border/box.
highlight of possible actions – currently, the pieces do have a highlight when they can be moved, but it's not super obvious (IMO). Ideally, this highlight would be the same color as the indicator that you can tap to add a peg to the piece, but when we were experimenting with this, that indicator had the highest contrast on both piece colors when it was stark white. (We also tried red, green, and limegreen. Other options might be yellow or coral.)
showing of previous turns – this is a requested feature, and it would be easiest to indicate this with a different color highlight, same as the selected state on pieces. But the color should be distinct from the others used here.

For all this stuff, it might be nice to get a visual designer to give some input.

mgrider / thrive-bga-project