Some of these differences and what the "game" deems as correct are just arbitrary and have no right/wrong.

And some of what they deem as right is arguably wrong, or at least is not right without additional context (such as which icons are hollow and which are solid). There is a valid reason for some icons being outlines while others on the same screen are solid.

This site is cute, and what they're trying to do is good; but I wouldn't pay them to build a UI.