Leaderboards
Your own best in every game, and where it sits among everyone else playing.
Each game keeps your best result, one for every difficulty. Some games count points, some count seconds, some count moves, and each of those gets a board of its own. In Sudoku the fastest finish wins. In Memory it is whoever turned over the fewest cards.
The board does not rank everybody, and that is deliberate. Near the top you get a place. Below that you get a percentile, for as long as reading one is still a pleasant thing to do. Everybody else sees their own record and nothing about position at all. No child is ever shown as last.
Names come from a fixed list: one adjective, one animal. Nobody types one, so nothing on the board identifies a child.
What it does not do: all of this lives on the device, so clearing your browser data clears the records with it. There is a backup code in the room, and it is worth writing down before the day you need it.