One more improvement. There needs to be some way to see the move the computer made. If you blink, a piece is somewhere else, and you have no idea what happened.
I like the concept of overlaying visualizations on chess to help people understand what's going on, but it will take a lot of playing with what to show and how to show it to make it useful rather than annoying.
Also, sometimes you see a red square around a piece, but it's not clear to me why. Is it present only when it is unprotected and an enemy piece is looking at it? That is kinda already too late, perhaps every unprotected piece could have the square around it.
And please give proper indication of what was the last move. I know most games will do this by coloring squares and you can't do this here, but having a way would be great, even if it was listing the move with chess notation below the board.
Also the pieces are a little weird to distinguish. I found myself trying to move Black's bishop twice.
After someone gave me feedback on lichess, I tried a heatmap instead (with green for white and red black), I'm not sure it's an improvement but you can see if you like it any better: https://taonexus.com/blunderfreechess2.html