The Online-Go Server (OGS) is a popular Go server. Since merging with nova.gs in October of 2013 it has become one of the fastest growing Go servers. OGS is especially popular with novice players due to the ease of setting up an account and the lack of external software required.
OGS was founded in November 2005 and was originally a turn-based / correspondence Go server. In October 2013 OGS merged with nova.gs to form the “New OGS”, a Go server offering both turn-based / correspondence and real-time play. The merge was announced on October 19, 2013.
OGS is based on HTML5 and runs in any modern browser. No installation of any other software and/or client is required. Features include analysis and review functions, demo boards with audio capability, site-wide and group tournaments and ladders, user-submitted Tsumego collections (Go puzzles), and more.
The easiest way to find a game on OGS is through the open challenge function. Players may create an open challenge based on the time, handicap, and rank-restriction settings of the player's choosing. The challenge will then appear on the site game graph as an open challenge. Players looking for a game may accept an open challenge by clicking on it and accepting.
Note: Strangely, the default setting for color selection is "Auto" and this automatically gives Black to the lower-ranked/rated player. You need to "Customize" the game and specify "Random" to get a usual random-color game.
Players may challenge individual users by typing the player's name in the search box and making a direct challenge. The settings are displayed to the challenged player, who may then choose to accept or reject the challenge.
OGS features regular sitewide tournaments for small and large boards on a rotating schedule. Players may join one of these tournaments at any time, although the tournament will only start if the player threshold is reached. Members of a " group" may also organize and join their own tournaments. Group creation is free.
The tournament settings have many features and a simple UI. Organizers control time and handicap settings and may choose a tournament structure from McMahon, Swiss, Round-Robin, and Single- and Double-Elimination.
See also OGSForumAllInOneDemocraticGame
Another source of competition may be found in the Ladder system. There is one sitewide ladder for each of the standard board sizes, and group members may also join their own local ladders if they desire. Each ladder lists players on a ranking from first to last. New players join at the bottom "rung" of the ladder and may challenge players who are ranked higher than they are on the ladder. A victory will cause the player to assume the challenged player's place on the ladder, causing all players ranked below to fall one rung. There is a game limit for number of challenges sent and received, so joining a ladder can provide a constant and minimally-intrusive means of securing correspondence games.
OGS features a handful of user-submitted bots which players may challenge. Players wishing to add a bot to the bot list may contact a moderator for setup instructions.
- OGS is a browser-based Go server. This means that no external software or installation is required in order to set up an account and start playing.
- Players may observe games by finding them on the site game graph, which organizes games by time setting and rank, or by by selecting "Observe Games," which allows players to view and select from multiple games at once based on a thumbnail of the board state.
- A Puzzles feature allows players to submit and solve collections of Go puzzles (tsumego). Players may also rate individual puzzles on a scale from one to five stars as well as submit feedback to the puzzle submitter.
- OGS features chat rooms in several languages as well as chat rooms for groups and group tournaments.
- Players may create and join groups in order to bring players with similar interests (Go related or not) together for chatting, local tournaments and ladders, and more.
- OGS displays Leaderboards which allow users to see which players are doing well recently. The leaderboards are not strictly rank-based, so anyone can appear on a leaderboard if their win rate is high enough for the week.
- OGS hosts a public forum for Go and non-Go related topics and discussions.
- OGS contains extensive reviewing tools which include a marking tool with numbering and lettering, branch creation and deletion, drawing tools, and audio support. Players may open a review after a game or in a unique demo board.
- OGS ReadMe
- OGS Forum
- OGS GitHub Wiki
- OGS/Nova merge announcement (quote by phelan on boardgamegeek.com, the original announcement page was lost; text quote below)
 OGS/Nova Merger Announcement 2013-10-19
(As quoted from the boardgamegeek.com page above)
anoek at nova.gs wrote:
Welcome to the new online-go.com!
Online-Go.com has joined forces with Nova.gs to bring to the Go community a state of the art web based go server! Here you'll be able to play both correspondence and live games, perform reviews in real time, voice chat with other players or spectators, and a whole lot more!
In addition to being an excellent place to play Go, OGS now has several features for Groups of players. So whether you have a local go club, an online study group, or just a group of friends, you can use OGS groups to create yourself a private forum, chat room, organize your members, and best of all run group tournaments and group ladders!
The already great tournament system of OGS had has been improved and extended, bringing in several options for tournament structures, controls, an advanced pairing algorithm, as well as adding the capability for users to create their own tournaments through the group interface. Additionally, we will be adding much better support for real time tournaments, automated tournaments, and some additional tournament structures in the near future.
While our core go server services (playing, reviewing, and running tournaments) will be ever evolving, we will also be focusing a lot on services, tools, and content for the Go community at large, so whether you choose to play here or at one of the many other excellent go servers out there, we hope to provide you with some interesting useful things in the near future, so stay tuned!
This merger marks a major accomplishment for all of us here and it wouldn't have been possible without the guidance and support of countless people throughout the community. Our sincere thanks goes out to all that have given us feedback, thoughts, ideas, bug reports, translations, media, moral support, and so much more. We aim to repay this help ten fold by giving back to the community an ever increasingly amazing site for Go players and by growing and enriching the Go community overall.
Thanks from all of us here!
To our existing users
Now to apologize! We know that this merge comes as quite a surprise for most of you. Hopefully after the shock wears off you'll see it as being a pleasant surprise! Normally we wouldn't keep such a large change as a surprise, but for various technical reasons, this was clearly the thing to do. So sorry for being secretive, it's not really our nature, hopefully you'll be understanding and forgive us :-)
To our nova.gs users
With this update we're bringing you the most requested feature, players! In addition to a large influx of new players we're also turning on site wide ladders, forums, and title tournaments! So please help us welcome the players coming from OGS, help show them around, and enjoy all of the new games to be had!
To our online-go.com users
There is a lot of new stuff for you to check out. This marks the third generation of server software used by OGS, which is an impressive feat for any online site! OGS has withstood the test of time and your new developers (matburt and anoek) are proud to be carrying the torch for the next leg of this journey.
We've worked hard to preserve all of your game history, active games, forums, tournament data, and just about everything else, so rest assured your history on OGS has been preserved. If you have questions, concerns, praises, bugs, or anything else please stop by the Chat, the developers and many people from the nova.gs server will be around a lot to answer questions and field issues. For bug reports, you may also want to use the bug reporting system found under the Help menu.
Unfortunately there's some bad news
During the migration process the old OGS server failed to produce the expected database backup for the 2013-10-18 and we had to use the backup from 2013-10-17 instead. This means an entire 24 hours of moves, game outcomes, and forum posts were lost. This is certainly not the way we wanted to start things off, but that's how they are, so we hope that you'll be understanding and in time forgive us. We worked long and hard to make sure all of your data was moved over to the new system appropriately, but unfortunately if we don't have the data we can't move it :-(
Never the less, we're hoping you'll find it in your hearts to overlook this somewhat major hiccup and enjoy the new site and all of the new features and functionality :-)
Some other notes about this merge:
Challenges have not been imported. If you've challenged anyone recently, you'll need to re-challenge them. Active games that have move times of 1 day have been changed to have 2 days to ensure no one times out because of the merge. All game clocks on active games have been increased to their maximum time for both players to help ensure no one times out as a result of the merge. All games which are in the stone removal phase must use the new system to select and agree upon the removed stones, so you may want to check up on any games that are in the stone removal phase.
- anoek, 2013-10-19