Terms of Service

Last updated: July 2026 · quantumchess.ninja

These terms govern your use of Quantum Chess (“the site”, “the game”), operated by Pura Viba LLC (“we”, “us”). By playing the game or creating an account you agree to them. If you do not agree, please do not use the site.

The service

Quantum Chess is a browser game. You can play against the built-in bots, locally with a friend, or online against other players — all for free, with no account required. An optional free account adds a rating and saved games. An optional paid Premium subscription adds extra features, described below.

Accounts

You must be at least 13 years old (or the minimum age of digital consent in your country) to create an account.
You are responsible for activity on your account and for keeping your sign-in credentials private.
Pick a username, avatar, tagline, and sayings that aren’t hateful, harassing, impersonating, or otherwise abusive. We may rename, remove, or disable content or accounts that break this rule.

Premium subscription & billing

Premium costs $3 per month (plus any applicable taxes) and renews automatically every month until you cancel.
Payments are processed by Stripe. Your card details go to Stripe directly and never touch our servers.
Cancel anytime: open your account panel in the game and choose Manage subscription, which takes you to Stripe’s billing portal. Cancelling stops future charges; Premium stays active until the end of the period you already paid for.
If we ever change the price, we will notify subscribers in advance, and the new price only applies from a later renewal — never retroactively.
Premium features may evolve over time. We may add, improve, or occasionally replace features, but we won’t materially strip Premium down while you’re paying for it.

One-time tip

Separately from Premium, you can leave a one-time tip ($5). A tip is not a subscription and never renews or charges you again. As a thank-you it removes ads for a year and unlocks one engine game review per day; tips stack, extending the ad-free window.

Refund policy

If you’re unhappy for any reason, email contact@quantumchess.ninja within 14 days of a charge — subscription or tip — and we’ll refund that charge in full, no questions asked.
Billing mistakes (duplicate or erroneous charges) are refunded whenever they happened.
Beyond the 14-day window, we don’t give partial refunds for unused time; cancelling instead stops all future charges.
Refunds are returned to the original payment method via Stripe and typically appear within 5–10 business days.

Fair play & acceptable use

Don’t cheat in online games (e.g. using engine assistance against human opponents), harass other players, or deliberately stall or abandon games to manipulate ratings.
Don’t attempt to disrupt, overload, reverse-billing, or gain unauthorized access to the service or other players’ accounts.
We may suspend or terminate accounts that break these rules. If a paid account is terminated for abuse, unused subscription time is not refunded.

Your content

You keep ownership of content you upload (such as an avatar or tagline). You grant us a license to store and display it as part of the game — for example, showing your avatar and tagline to your opponents. We may remove content that violates these terms.

Availability & disclaimers

Quantum Chess is an independent project provided “as is”. We work to keep it fast and reliable, but we don’t guarantee uninterrupted availability, and online games may occasionally be disrupted by maintenance or outages. To the maximum extent permitted by law, we disclaim all warranties, and our total liability to you for any claim relating to the service is limited to the amounts you paid us in the 12 months before the claim.

Changes to these terms

We may update these terms; material changes will be reflected by the “last updated” date above, and continued use of the site after a change means you accept the updated terms. Changes to subscription pricing are always communicated in advance as described under Billing.

Governing law

These terms are governed by the laws of the State of Hawaiʻi, USA, without regard to its conflict-of-law rules.

Contact

Questions, billing issues, or refund requests: contact@quantumchess.ninja.