Effective date: 30 September 2026
These terms govern your use of the TheoryChess website and service (the “Service”), run by Hasan Süzen. By using the Service or creating an account you accept these terms. If you do not accept them, please do not use the Service.
1. The Service
TheoryChess is a training tool for learning chess openings by playing against the engine, taking quizzes and reviewing with spaced repetition. The opening catalogue, training, quizzes, spaced repetition and analysis are free. Content, features and scope may change over time; significant changes that affect you directly are announced on the site.
2. Premium, the beta and the free report
- Premium features: game reports and opponent prep are Premium features.
- Beta: during the beta, Premium features are free for everyone signed in. The end of the beta is announced on the site in advance.
- Free report: once the beta is over, every account without Premium can get one free report on its own games. If the report cannot be made (for example, the username is not found), the free report is given back.
- Getting Premium: Premium cannot be bought yet; an admin may give it for a set period. When paid Premium is offered, the price, payment, right of withdrawal and cancellation terms will be set out separately and clearly before any purchase. Nothing in these terms creates an obligation to pay.
- Interest in Premium: the “I’m interested in Premium” option only records your interest; it does not lead to any email or other commercial message and can be withdrawn at any time.
3. Game reports and opponent prep
- Reports are made from games that are public on lichess and Chess.com. Those sites are independent of TheoryChess; making reports depends on their availability and rules. When they are busy or apply request limits, reports are made in turn and may be delayed.
- In “My game report” you should only type the username of an account that is yours.
- Opponent prep is for chess preparation only. It may not be used to harass or stalk other players, to build bulk profiles of them, or to publish what you learn in a way that demeans them.
- Limits: at most 20 reports a day, one report being made at a time, and at most 20 games per report. The latest 10 reports per account are kept, each for at most 90 days.
- Theory comparisons and engine verdicts are produced automatically and are not promised to be error-free (see section 7).
4. Your account
- You create an account by signing in with Google. You are responsible for the security of your account and of the linked Google account.
- Accounts are personal; they may not be transferred or opened on someone else’s behalf.
- Children under 13 may not create an account. Users under 18 should use the Service with a parent’s or guardian’s permission.
5. Acceptable use
When using the Service you agree not to:
- use it for unlawful purposes or in a way that infringes others’ rights,
- try to disrupt it, overload it or get around its security measures,
- collect data in bulk with automated tools outside the interfaces made available,
- try to access another user’s account or impersonate someone else,
- set up schemes to obtain scores or results misleadingly,
- use several accounts or automated tools to get around report limits or the free report.
6. Intellectual property
The site’s design, text, blog posts and the TheoryChess name and logo belong to Hasan Süzen and may not be copied or used commercially without permission. The open-source components used in the Service (the Stockfish chess engine, the opening dataset, the piece artwork and the 3D model) are subject to their own licences, and nothing in these terms restricts the rights those licences give you. See Licenses and Credits.
7. About the analysis
Move evaluations, commentary, quiz results and game reports are produced automatically using the Stockfish chess engine and an open opening dataset. They are for training purposes; they are not promised to be error-free, to lead to any particular result or to bring success in competition.
8. Availability
Reasonable care is taken to keep the Service running without interruption or error, but maintenance, faults or problems with third-party services may cause interruptions. The Service may be discontinued in whole or in part; where possible this will be announced in advance.
9. Suspension and closure
Accounts that break these terms seriously or repeatedly may be suspended or deleted. You may close your account at any time yourself from the account settings or profile page, or ask for it to be deleted by writing to [email protected] from the email address registered to your account. A closed account and its data cannot be restored.
10. Limitation of liability
The Service is provided “as is”. To the extent permitted by applicable law, no liability is accepted for indirect damage arising from the use of, or inability to use, the Service. This limitation does not affect liability for intent or gross negligence, or the mandatory rights you have under consumer law.
11. Third-party links and services
The Service may link to third-party websites (for example, the lichess and Chess.com game links in reports). Their owners are responsible for their content, rules and privacy practices.
12. Changes
These terms may be updated. The current version is published on this page with its effective date. Significant changes are announced on the site; continuing to use the Service after a change means you accept the updated terms.
13. Governing law and disputes
These terms are governed by the laws of the Republic of Turkey, and the courts and enforcement offices of the Republic of Turkey have jurisdiction. Users acting as consumers keep their right to apply to the consumer arbitration committees and consumer courts where they live, and any mandatory protection given by the law of their country of residence.
14. Contact
Questions about these terms: [email protected].