Good game for brain sharpness! At first I thought I needed a calculator to play the game, but I soon realized that using a calculator defeats the purpose. It is, in fact, a lot of fun to do the large-number estimating plus the final answer calculations and one's head. I don't mark the simple format of the game. I like it because it takes me back to a bygone era. The author could spruce it up soon, and that would be nice. Adding an improvement to the tutorial on how the first time player also, in particular by showing the addition or subtraction to the number in the top right corner. Also how does one get 16 from 27-3 minus one? I haven't quite figured that one out.
By the way, I found this game through your pool or billiards game, which is