Two pieces of data, both inside your browser: recently opened games and earned badges.
This page is short because there is very little to describe.
Local storage holds the list of games you opened recently and any badges you earned. Both are stored by your own browser on your own device.
No accounts, no email addresses, no analytics identifiers, no advertising cookies, no third-party trackers.
Clear your browser's site data for this domain and both are gone, permanently.
If this ever changes it will be stated here in plain language on the day it changes.