Terms of Service

Last updated: September 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 Free bot roster, locally with a friend, or online against other players without paying. An optional free account adds a rating, saved games, and persistent bot unlocks earned after completed human matches. An optional Premium purchase unlocks game review, eight Premium bots, all extra avatars and the other features described below with one payment.

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 & one-time payment

Premium costs $10 once. There is no monthly plan, automatic renewal, or further payment required to keep your unlock.
Isaac Steinitz is available from the start. Fifteen other bots are earned one at a time after completed human matches (win, loss or draw), on both Free and Premium accounts. Buying Premium does not skip these match unlocks.
The unlock is permanent on your account and includes unlimited engine game review, all eight Premium bots immediately, all extra avatars, character taglines and sayings, custom profile features, up to 1,000 saved games, and no ads.
Payments are processed by Stripe. Your card details go to Stripe directly and never touch our servers.
Existing paid customers keep Premium without paying again. Future price changes will not create additional charges for an account that has already unlocked Premium.
Premium features may evolve over time. We may add, improve, or occasionally replace features, but we won’t materially strip down your purchase.

Refund policy

If you’re unhappy for any reason, email contact@quantumchess.ninja within 14 days of a charge and we’ll refund that charge in full, no questions asked.
Billing mistakes (duplicate or erroneous charges) are refunded whenever they happened.
The 14-day refund window applies to the one-time Premium purchase.
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 matchmaking or results.
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, the Premium purchase is not refunded for unused access.

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. An existing Premium unlock never requires a renewal payment.

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.