These are the Go applications that I use the most.
KGS is a fantastic English-language realtime Go server, created by wms. The client is a Java program, so it works fine on Windows and Linux as well. Basic accounts are free, and give you access to almost all of the features of the server. You can play in rated and non-rated games, access your game history, download SGF files of your games, comment and review your own games, and join the chat channels. The client also works as an SGF creator and editor, letting you take notes and review variations from your games. This is the best client I’ve found yet for handling multiple games in a single SGF file and easily navigating heavily nested trees.
Here is an example of a game under review. You can do this offline with downloaded SGF files, or you can review online by loading the game into a chatroom. Then other people can join the review. Anything that people type will appear at that point in the SGF file. We use this mode during our class matches to review with each other prior to emailing the game record to the instructors.
Finding a game is pretty easy, since the main tab is a list of all open games. They come and go quickly though, so by the time you’ve decided to join one it’s probably already filled. I prefer to use the automatch feature. Most of the time it finds an opponent immediately. Depending on the time of day, it might take a few minutes.
Paid accounts add the ability to join tournaments and watch professional lectures. You can view the lectures live and interact with the instructor via chat. They are also stored in an archive to watch later.
I used a free account for years, but earlier this year switched to a paid account. Given the amount of time I spend playing and studying on this server it’s a bargain. Android uses should take note that the $15 app comes with two months of KGS+ included. If I had an Android phone, I would buy this without hesitation. Since KGS uses Java for its client, wms has said in no uncertain terms that there will not be an iOS version released anytime soon.
Life in 19x19 has a dedicated KGS forum where wms posts.
Goban is a client for playing against GNU Go. Computers aren’t good at Go, but they can still crush newbies. If you’re new the game, playing 9x9 games repeatedly against GNU Go is a good way to get better. Start with a 4 stone handicap and keep at it until you can beat the computer with no handicap.
One quirk of this program is that the board size isn’t found in the preferences. It’s in the info drawer.
SmartGo Kifu is awesome. It’s not without its quirks and faults, but it’s a fine piece of software. By far the biggest thing that I use it for is the set of 2000+ tsumego problems. Most of them are life & death problems, with a few fuseki and tesuji problems thrown in. They are organized by difficulty, and problems that you get wrong are marked so that you can go back and retry them later. It’s similar to Go Grinder, but I like the SmartGo interface much better.
A major feature that I am just starting to use is the database of 31,000 professional games. Only 20 are annotated, and the review features are not as easy to use as KGS. I’m not strong enough to get much out of a pro game that isn’t commented. I would guess that stronger players would have a lot of fun with a portable database like this.
There’s an AI, with all the caveats of computers being weaker than humans. It still plays a decent 9x9 game, and will destroy newbies who don’t take a handicap.
You can play against other humans, but only on the same devise. There is no network play built in. I haven’t found this to be an issue, since I play online via KGS or just use one of the turn-based web sites for playing on the iPad. It keeps a history of games played, organized by player, so you can review your games later.
iPhone users should check out SmartGo Pro. It’s the predecessor to Kifu, and has the pro database and the Go problems included.
Tengen is a decent, not great, Go client for IGS. I’m not a fan of IGS to begin with, but when I absolutely must play a real-time game on the iPad it’s the only option that I’m aware of. (There’s another iPhone IGS client called Tetsuki, but uninstalled it after having connection problems.)
A nice bonus with web-based Go servers is that they are equally useful on the Mac and the mobile devices. Almost all of the Go games that I play with the iPad are done on a web server.
Dave Peck Go
This is a simple, yet polished, web client for playing turn-based games. There are no accounts, game histories, archives, or rankings. You set up a game, plug in the email addresses of both players, and then each of you receive a link in your email and a reminder when it’s your turn. It runs on Google’s App Engine, and is an open source project.
Dragon Go Server [DGS]
DGS is a full-featured server with accounts, ratings, a ton of game options, and a generally pleasant user base. I usually start or join games with extremely long time controls, averaging less than one move per day. Many people on this server are fine with such slow games, and are typically involved with multiple games at once. The interface is usable, and generally doesn’t get in your way. You click where you want to move then confirm the move. You can pull up lists of your games, completed or in progress. Reviews need to be done externally, which usually means that you download the SGF file and load it in CGoban (the KGS client).