MoonDoku
Privacy policy
Last updated September 29, 2026
MoonDoku is a Sudoku game. We collect what the game needs to work and to remember your progress, and nothing we don’t need. We don’t sell your data, and we don’t run advertising.
Playing without an account
You can play tonight’s Nightly with no account and no sign-up. When you do, we set a
guest_id cookie so your puzzle,
score, and achievement progress survive a page reload. If you later create an account, that guest
progress is migrated onto it and the cookie is retired.
If you choose a language at the bottom of a page, a
moondoku_locale cookie remembers
it, so the site keeps speaking that language on your next visit. It holds only the language you
picked, lasts about a year, and stays after you sign out.
Your device also stores preferences and progress locally — the theme you picked, your cat’s coat, your Nightly streak and constellation history, and whether you’ve seen the welcome. That data lives in your browser (or app) and is only sent to us when you’re signed in and it syncs to your account.
If you create an account
We store:
- your email address and display name, and the profile icon you choose;
- your gameplay record — puzzles played, completion times, scores, mistakes, hints used, achievements earned, themes tried, and which Nightly dates you’ve solved;
- if you sign in with Google or Apple, the account link they give us and the name and email address they share (we never receive your password);
- if you buy the full game, your Stripe customer reference and the date of purchase. We never see or store your card details — those go directly to Stripe.
Sign-in is passwordless: we email you a one-time link, or you use Google or Apple. We don’t store
passwords at all. On the website, a
moondoku_last_sign_in cookie
remembers which of those you used last, so the sign-in screen can mark it “Last used” next time.
It holds only the method — never your address — and stays after you sign out.
Analytics
We use PostHog to understand how the game is used — pages viewed, puzzles started and completed, hints used, sign-ups. If you’re signed in, those events carry your account id and whether you own the full game. Your name and email stay in our database and are not sent with them. We use it to make MoonDoku better, not to profile you for advertising.
The Steam edition also reports errors the game runs into — what failed and where in the game’s code, with the folder it’s installed in taken out — so we can fix crashes on computers we don’t have. Settings › Privacy in the Steam edition switches off these reports along with the analytics above.
On the website, PostHog also records a replay of your visit — what you clicked and how the page responded — so we can see where the game confuses people. Anything you type into a field is masked before it leaves your browser, but text already on the screen is part of the recording: on a signed-in page that includes your display name, and on the page that confirms a sign-in link it includes the address you asked us to send it to. The iPhone and Steam apps record nothing.
Who we share it with
Only the services that make MoonDoku run, and only what each one needs:
- Stripe — payments and card processing;
- Resend — sending sign-in links and account email;
- PostHog — product analytics;
- Google and Apple — only if you choose to sign in with them;
- our hosting provider — running the servers and storing the database.
If you use the iOS app or the Steam edition, Apple and Valve handle those purchases and have their own privacy policies.
Keeping and deleting your data
We keep your account data for as long as your account exists. You can delete your account at any time from Account settings, or from the app — deleting it removes your account, your saved games, your achievements, and any access tokens issued to your devices. Deletion is permanent and we can’t recover it afterwards.
Guest progress isn’t attached to an identity we can look up, so clearing your browser’s cookies and site data removes it.
Your rights
Depending on where you live, you may have the right to access, correct, export, or delete the personal data we hold about you, and to object to some processing. Email support@moondoku.com and we’ll help — we’d rather sort it out directly than make you file anything.
Children
MoonDoku isn’t directed at children under 13, and we don’t knowingly collect their personal data. If you believe a child has given us data, write to us and we’ll remove it.
Changes
If this policy changes in a way that matters, we’ll update the date at the top and, for significant changes, tell account holders by email.