Feature request: user-defined lock of selected circles, similar to how the existing red circles are locked. (This is like the Minesweeper flag option)
Another feature request... if a tile is already illegal (too many committed blue in line of sight, or no way to commit more blue to satisfy requirement), flag it already. I think the biggest pain is the counting. Otherwise, a nice game!
If you start adding any automated processing like that, then you're only a couple more processes away from the game just solving itself without you.
The elegance of this implementation is that you are doing all the solving. Unless you specifically ask for help from the hint button.