Until now the score was a number in your own browser. Clear the cookies, or open the site on your phone, and the count was gone.

Every round is recorded on the server now, tied to an anonymous player id that your browser keeps, and merged into your account the moment you sign in. Nothing is lost on the way, and nothing is counted twice.

It also makes the leaderboards honest: they only list players who signed in, and the score you read is the same one the ranking is built from.