The following guidelines are what they are: guidelines. Please keep the experience of players in mind when creating/approving contributions.

Disagree with the current guidelines? Let us know in the forum

General Guidelines

  1. Contributions must be written in English.

  2. The description must be clear and unambiguous. (for all games but reverse CoC)

    	- Keep it clear and consise
    	- Avoid flavour text
    	- Don't address the reader directly
    	- Avoid controversial topics
    	- Don't overlook the protocol

    => Writing the statement

  3. The default code must be working for all languages.

    => Stub generator syntax

  4. Test cases must be properly defined. (for all games with test cases)

    	- Test cases should cover all specifications
    	- Each validator must differ from the corresponding test
    	- Each validator should check the same case as the corresponding test
    	- The first test case must be a simple one

    => Defining test cases

  5. Contributions must be original. (for all games but Clash of Code)

Specific Guidelines

Clash of Code

The main goal of a CoC battle is to be solved in a short period of time. CoC players are looking for quick simple puzzles to solve; for more complex problems, they'll dive into the classic puzzles section.

  1. No CoC puzzle is too easy.

    In theory, no CoC puzzle should be rejected with the justification that it's too simple. However, moderators should reach an agreement on whether a trivial CoC contribution is worth being added to the pool of CoCs.

  2. CoC close duplicates are not forbidden.

    Moderators should reach an agreement on whether duplicate versions of a puzzle can be accepted or not. Copy-pasting an existing CoC puzzle is obviously not allowed.

  3. CoC statements should be self-sufficient. (doesn't apply to reverse puzzles obviously)

    When your time is counted, as a player, you don't want to waste time searching for a formula or a definition online to understand what needs to be done.

  4. Binary or language-specific outputs should be avoided in CoC.

    Some output formats favor specific languages and make the contribution unbalanced. Binary outputs open the door to "cheating" solutions to get around 50%.

Optimization Puzzles

  1. It must be very difficult to approach the optimal score.

Games created with the sdk

  1. The referee program should be robust and reliable.

    	- The referee must end a player's program when receiving an unrecognizable command.
    	- The referee must send an error message in the console when receiving an invalid but recognized command.
    	- The referee must stop the game early if the game is stale or already decided.
    	- The referee must not crash. All exceptions must be caught.
    	- Indices must start at 0, not 1. The origin is always the top left pixel/tile.
  2. The graphics are clear and represent the progression of the game well.

    	- The graphics must be self-explanatory. _A player should understand most of the rules from a replay_
    	- The graphics must contain the avatars and nicknames of current players (if bot programming).
Create your playground on
This playground was created on, our hands-on, knowledge-sharing platform for developers.
Go to