Multiplayer Chess

Playing chess online against other humans is fun, but if you have any difficulties, head here and find answers.

Why did the game end unexpectedly?

Multiplayer games may end unexpectedly due to connection issues on your – or your opponent’s – side.

The multiplayer service has an uptime of 99.99%. On any day, about 10,000 people connect and anywhere from 30,000 to 50,000 games are being played. Frustrating as it may be, only 1% of them end unexpectedly.

In general, a game will end abruptly when one player can communicate correctly with the server but their opponent can’t.  Unlike real-time FPS multiplayer games for example, chess cannot be fault tolerant. In a real-time game one player may miss one or more updates from the server and still keep playing (often the player sees the enemy “jump” from one place to another). But as chess is turn-based, players must be in perfect sync – one player can’t just move twice or ignore a non-responsive opponent!

A player may miss a server move due to many reasons: a bad internet connection or a browser bug are just some of the culprits. For example, Google Chrome can ignore a move received from the server if the browser tab is not active. Or a player may not be connected to the internet and not realize it as the system still reports it as being up.

If you receive a message that the game is out-of-sync and it has ended, it usually means that there was a miscommunication between you, the multiplayer service and your opponent. Since version 10.8.7 we made sure you don’t lose any points in this case.

If a game ends unexpectedly in Draw, it’s because your opponent is unresponsive and, despite being online, did not receive the move in time (you should see the message “Sending Move” for some time before this happens). The Multiplayer service cannot “punish” your opponent by declaring you the winner and can’t know if a Draw suits you.

If you lost any points due to a game ending unexpectedly, please contact us mentioning your username, your opponent’s username, the date & time the match took place and the number of points you lost.

Why did the game end unexpectedly in draw?

A game may end unexpectedly in Draw if your opponent is unresponsive and, despite being online, did not receive the move in time (you should see the message “Sending Move” for some time before this happens). A player can be unresponsive for many reasons, including a network issue on their side or an old device.

The Multiplayer service cannot “punish” your opponent by declaring you the winner and can’t know if a Draw suits you. If you are unhappy with the result, please contact us mentioning your username, your opponent’s username, the date & time the match took place and the number of points you lost.

Can I play correspondence chess?

SparkChess was designed for quick games. Few players have the patience for correspondence chess and there were very few requests for us to add this. If you think we should support correspondence chess, please contact us. In the meantime you can use a site like FICGS.

What is the meaning of the Connection Quality icons?

We have added Connection Quality Indicators for the multiplayer service. At this time they are experimental and are shown at the bottom of the Invitation Window.

They look like this:

SparkChess Multiplayer Connection Quality Indicator

From left to right, here’s what the icons mean:

  1. The bars show the network latency (also known as “ping time” or “round-trip time”), which means the amount of time needed for information to travel from your device to the SparkChess multiplayer servers and back. 4 green bars indicate a fast and stable network connection, while 1 red bar shows a slow and potentially unstable one. The number of bars you get depend on your physical location (users in North America are more likely to get 4 bars) and connection type. A laptop Ethernet connection will always be faster and more stable than a slow 2G cellular one.
  2. The Socket icon indicates whether your connection is through a web socket or by HTTP fallback. A green socket connection indicator means there’s a dedicated communication channel open between your device and the SparkChess multiplayer server. They are very fast but if the connection breaks due to your internet connection, you may get quickly disconnected from the server. HTTP fallback is much slower; it may not be affected by intermittent issues but this also means it may not detect immediately when your network is down. 93% of the connections to SparkChess are made via socket connections. HTTP fallback is used only if, due to peculiarities of your network, a socket connection cannot be established.
  3. The Lock icon indicates an encrypted connection. If you play SparkChess online through a secure HTTPS connection, the connection to the multiplayer server is required to be SSL-encrypted as well. Otherwise we don’t encrypt connections because encryption slows down the communication a bit. Given the nature of a multiplayer chess game, we believe encryption is not necessary. If you think we should always encrypt connections, please let us know.

How does filtering work in multiplayer?

Because the number of available players is changing constantly, Full Version owners may filter the Invitation list based on their preferences.

Currently the following filters are available:

  • by score: with this filter enabled, only players within 10% of your score will be shown. So if you have 1000 points, you’ll see only players with at least 900 points and at most 1100 points.
  • by subnet: The filtering is done by IP address. Only players with IP addresses from your “virtual neighborhood” are shown (technically speaking it’s a Class-C subnet). This usually means only players from the same building or block, although it depends on your Internet provider. This mode is perfect when you want to play with a coworker or at home with another person in the same house.
  • by country: only players determined to be in the same country as you are shown. This method may not be always available. Players who’ve just created accounts may not have their country determined yet.

We should mention that your location (both the IP and the country) are safe. Another player cannot learn your location.

Did my account disappear?

Free accounts may be removed if unused for prolonged periods. From time to time we purge inactive accounts. The “grace period” is dynamic and calculated based on many factors. We do want to reward active users and we need to conserve resources (storage is not free and having a few Gb of unused accounts doesn’t help); we also need to backup the databases and maintain them, which requires more CPU power.

Accounts may also be removed if they contain offensive names.