What do we store? A guest only has a generated name, which disappears after a day. An account holds your name, e-mail address, password (encrypted), avatar, ratings, game and tournament history, friends and blocks.
Why? So that games, ratings and history work. We do not sell data or combine it with other sources.
Cookies. Our own cookies remember your sign-in and the language you picked. Ads are shown by Google AdSense — on your first visit Google asks for consent to its advertising cookies; without it, ads are not personalised.
Chat and reports. Chat is not stored, and messages with swear words are not sent. The server only remembers your messages from the last hour: if someone reports you, they are attached to the report as evidence. Reports and moderation decisions are kept so they can be explained later.
Your data. In your account settings you can download a file with everything we hold about you, or delete your account (30 days to change your mind). Games you played stay, but without your name.