This is nice, it feels good to use it. Nothing feels extra, all the features are quite polished.
Areas of play could be made, like big rectangles with a tagg added, there could also be pieces to be moved around.
Glad to know you like the tool.
Regarding pieces, do you mean some kind of icons/shapes? Should they have color, text, etc?
I've added an "Area" object based on your suggestion. You can edit the title and resize it using the handle on the bottom right. Do try it out and let me know if it's what you wanted. Happy to further improve the tool based on your feedback.