Yin-Yang

Yin-Yang is a logic puzzle with simple rules and challenging solutions.

The rules are simple. Yin-Yang is played on a rectangular grid with no standard size. Some cells start out filled with black or white. The rest of the cells are empty. The goal is to color all cells in such a way that:
1. All black cells should be connected orthogonally in a single group.
2. All white cells should be connected orthogonally in a single group.
3. 2x2 areas of the same color are not allowed.

These 3 simple rules lead to some complex deductions, which are not so obvious. There are 2 important lemmas based on them, without which even the easy Yin-Yang puzzles seem very hard or even impossible to approach. You can learn these lemmas in the video tutorial below.

Video Tutorial

Hide the rules

Become a Patron

Feedback | Specific puzzle

Mass Print | Hall of Fame | Statistics

Content & Nickname Policy

A. Scope

Our puzzle websites and apps publish original, programmatically generated logic puzzles. They contain no user-generated content other than player nicknames displayed on leaderboards. There are no comments, chat rooms, forums, file uploads or user profile pages, and puzzles are solved with clicks and selections rather than free-text input.

B. Nickname rules

Nicknames must be 3–15 characters long and may contain only letters and digits. Special characters, spaces, links and email addresses are not technically possible.

Nicknames may not contain profanity, slurs, or references to sexual content, violence or drugs, in any spelling or combination.

Nicknames may not impersonate other people, brands or staff.

C. Screening and enforcement

Every nickname is automatically screened before it is accepted — at registration, on profile change and on social sign-up. A nickname that fails screening is rejected and never appears on the site.

New accounts receive a neutral, system-generated nickname by default.

As an additional safeguard, restricted terms are masked at display time.

The entire user base is re-screened in automated audits, run regularly and whenever the screening rules are updated. Nicknames found in violation are renamed to a neutral Player format, and an audit record is kept.

D. Reporting

To report a nickname or any other concern, use the contact or feedback link available on every page. Reports are reviewed and acted on promptly.