PlayStrategy supports There are over 30 different games/variants, including 10 chess variants and 10 draughts variants..

PlayStrategy time controls are based on estimated game duration = (clock initial time) + 40 × (clock increment)
For instance, the estimated duration of a 5+3 game is 5 × 60 + 40 × 3 = 420 seconds.

• < 29s = UltraBullet
• < 179s = Bullet
• < 479s = Blitz
• < 1499s = Rapid
• ≥ 1500s = Classical

On PlayStrategy, the main difference in rules for correspondence chess is that an opening book is allowed. The use of engines is still prohibited and will result in being flagged for engine assistance.

In the event of one player running out of time, that player will usually lose the game.

However there are some special cases for chess. The game is drawn if the position is such that the opponent cannot checkmate the player's king by any possible series of legal moves (FIDE handbook §6.9).

In rare cases this can be difficult to decide automatically (forced lines, fortresses). By default we always side with the player who did not run out of time.

Note that it can be possible to mate with a single knight or bishop if the opponent has a piece that could block the king.

In both Chess and Lines of Action, if a position occurs three times, players can claim a draw by threefold repetition. PlayStrategy implements the official chess FIDE rules, as described in Article 9.2 (d) of the FIDE handbook §9.2.

We did not repeat moves. Why was the game still drawn by repetition?

Threefold repetition is about repeated positions, not moves. Repetition does not have to occur consecutively.

We repeated a position three times. Why was the game not drawn?

Repetition needs to be claimed by one of the players. You can do so by pressing the button that is shown, or by offering a draw before your final repeating move, it won't matter if your opponent rejects the draw offer, the threefold repetition draw will be claimed anyway. You can also configure PlayStrategy to automatically claim repetitions for you. Additionally, fivefold repetition always immediately ends the game.

The centipawn is the unit of measure used in chess as representation of the advantage. A centipawn is equal to 1/100th of a pawn. Therefore 100 centipawns = 1 pawn. These values play no formal role in the game but are useful to players, and essential in computer chess, for evaluating positions.

The top computer move will lose zero centipawns, but lesser moves will result in a deterioration of the position, measured in centipawns.

This value can be used as an indicator of the quality of play. The fewer centipawns one loses per move, the stronger the play.

The computer analysis on PlayStrategy is powered by Stockfish.

One minute after a player is marked, their 40 latest rated games in the last 3 days are taken. If you are their opponent in those games, you lost rating (because of a loss or a draw), and your rating was not provisional, you get a rating refund. The refund is capped based on your peak rating and your rating progress after the game.
(For example, if your rating greatly increased after those games, you might get no refund or only a partial refund.) A refund will never exceed 150 points.

If your opponent frequently aborts/leaves games, they get "play banned", which means they're temporarily banned from playing games. This is not publically indicated on their profile. If this behaviour continues, the length of the playban increases - and prolonged behaviour of this nature may lead to account closure.

It’s not possible to apply to become a moderator. If we see someone who we think would be good as a moderator, we will contact them directly.

In general, usernames should not be: offensive, impersonating someone/something else, or advertising.

No, usernames cannot be changed for technical and practical reasons. Usernames are materialized in too many places: databases, exports, logs, and people's minds. You can adjust the capitalization once.

Ratings are calculated using the Glicko-2 rating method developed by Mark Glickman. This is a very popular rating method, and is used by a significant number of chess organisations (FIDE being a notable counter-example, as they still use the dated Elo rating system).

Fundamentally, Glicko ratings use "confidence intervals" when calculating and representing your rating. When you first start using the site, your rating starts at 1500 ± 1000. The 1500 represents your rating, and the 1000 represents the confidence interval.

Basically, the system is 95% sure that your rating is somewhere between 500 and 2500. It is incredibly uncertain. Because of this, when a player is just starting out, their rating will change very dramatically, potentially several hundred points at a time. But after some games against established players the confidence interval will narrow, and the amount of points gained/lost after each game will decrease.

Another point to note is that, as time passes, the confidence interval will increase. This allows you to gain/lose points more rapidly to match any changes in your skill level over that time.

The question mark means the rating is provisional. Reasons include:

• The player has not yet finished enough rated games against opponents of similar strength in the rating category.
• The player hasn't played enough recent games. Depending on the number of games you've played, it might take around a year of inactivity for your rating to become provisional again.

Concretely, it means that the Glicko-2 deviation is greater than 110. The deviation is the level of confidence the system has in the rating. The lower the deviation, the more stable is a rating.

The asterisk means the rating has been input. This has been done as part of the setup for a handicapped tournament as the player does not have an accurate rating on PlayStrategy yet.

In order to get on the rating leaderboard you must:

1. be in the top 10 in this rating.
2. have played a rated game within the last month for this rating,

The 2nd requirement is so that players who no longer use their accounts stop populating leaderboards.

Every Shield tournament that has been played in the last 2 months counts towards the Shield Leaderboard. This includes both Variant Shields and Medley Shields. The following points are awarded from each Shield:

1. 1st Place: 5 points
2. 2nd Place: 3 points
3. 3rd Place: 2 points
4. Played at least one game: 1 point

The only other restriction is that a player can only use their best score from the same shield in their leaderboard score. For example if a player comes 2nd in the most recent Lines of Action shield but came 1st in the previous Lines of Action shield, then they will only have 5 points (for the 1st place) counting towards their total score.

It is best not to think of ratings as absolute numbers, or compare them against other organisations. Different organisations have different levels of players, different rating systems (Elo, Glicko, Glicko-2, or a modified version of the aforementioned). These factors can drastically affect the absolute numbers (ratings).

It's best to think of ratings as "relative" figures (as opposed to "absolute" figures): Within a pool of players, their relative differences in ratings will help you estimate who will win/draw/lose, and how often. Saying "I have X rating" means nothing unless there are other players to compare that rating to.

Enable Zen-mode in the display preferences, or by pressing z during a game.

Unfortunately, we cannot give back rating points for games lost due to lag or disconnection, regardless of whether the problem was at your end or our end. The latter is very rare though. Also note that when PlayStrategy restarts and you lose on time because of that, we abort the game to prevent an unfair loss.

PlayStrategy can optionally send popup notifications, for example when it is your turn or you received a private message.

Click the lock icon next to the playstrategy.org address in the URL bar of your browser.

Then select whether to allow or block notifications from PlayStrategy.