I don't know quite what happened, but I changed from the 9x9 to the 13x13 playing against the computer. It was not good. I could win a fair number of games on the 9x9, but I lost big time on the 13x13. If I could put my finger on it, I didn't spread out enough, but the computer spread out plenty and seemed to be attacking from all directions. The first time I think I ended up with no territory captured. So is it that big a change for others to play on the larger boards?

The 9x9 board is all about local tactics and fighting. These, along with life and death, are the heart and soul of go, so it makes sense to learn them first. When you move to the 13x13 board, there is more space so that what happens in one corner or on one side doesn't seem to affect the opposite one. It does, but more subtly. In addition, while very slow solid moves are quite usable on a 9x9 board because they are good in a fight, efficiency matters more on a larger board, because there is more space and more moves for an efficiency difference to become noticable. This means that you will need to play and learn to use faster and looser moves.

One thing you'll see is that on the 13x13 board (and larger) the two space extension along the side becomes the ruler by which you measure things along the edges. Making sure your groups have access to the center is also very important, so that your opponent doesn't make a ton of points there while you don't get compensation elsewhere. Lastly, if you habitually play on the star points, on a 13x13 board they are one line farther from the edge, which completely changes their meaning. Now they are meant for fighting and influence, and not just for territory taking.

If you have a game example you can upload here to take a look at, I (or someone else) may be able to provide more specific suggestions.

Yes, 19x19, 13x13, and 9x9 are almost 3 (completely) different games.

Let's try to look at this in reverse.

The goal is to play on the full board of 19x19. If, as a total beginner, you started with that your play would tend to be too local. It would take you a long time to learn that play in one area exerts a subtle effect in more remote parts of the board. Once you are playing well, what the difference in these subtle effects will be influences your choice among local play alternatives.

So ....... you start out learning in 9x9 where because nothing is far away the effects are very strong, more obvious. In effect, it is all local.

You are now graduating to 13x13 where because distance is greater the effect of a play in one part of the board on other parts of the board has become a little more subtle. But hopefully your experience with 9x9 will let you look for these effects, to notice them. You will need to learn about some standard sequences as there may now be more moves between beginning and final consequences. I'd begin by learning things like "what is a ladder?".

But take what I have just said about the progression of learning with some salt. I did not learn by starting out on the smaller boards. I'm one of those rarer folks who learn well from books and examples. I learned on the big board and didn't have any opponents to play against at the time and was about 10-12k when first playing against an opponent. Most people can't learn they way I did.

I think it would be more straightforward to say that a 9x9 is smaller, so there's less to look at, so it's easier to keep track of something. Surprisingly, a bad ladder is every bit as bad on 19x19, or even 37x37, as it is on 9x9... it's easier to forget the 19x19 ladder breaker because it's six inches further away, not because it is less ladder-break-y. In fact, because there is so little territory to be had on a 9x9 board, I would say that 9x9 is the game where the subtle effects of every stone ripple across the board; you always need to have the precise amount of territory you need to win in view, and every stone affects that total. In 19x19, you can just play a solid middlegame and endgame and expect to get back on one side what you lose on the other side.

The biggest difference between 9x9 and 19x19 is that 19x19 is four times as big, and there are four times as many (very important and fairly obvious) relationships between stones to keep track of. That makes the games last four times as long, if not longer. Go is a game that calls for a lot of mental stamina, but you don't really figure out how much until you move to the bigger boards. It's hard for anyone to stay focused for 1-2 hours, and beginners normally completely lose track of what's happening on other parts of the board.

I imagine that's the main reason you've had an adjustment. Of course, it's also possible that the program you're playing does better on bigger boards - I seem to recall that this was true of GnuGo, for example.

I've been playing go for a long time. I've gone from what I think was about 12-9 kyu to 17-15k over the last several years by not playing much. I got some go software for the iPad and iPhone. I cannot win at 9x9. I can win and progress up the kyu ladder at 13x13 but cannot win at 9x9.

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David Bogie, Boise ID
I play go, I ride a recumbent, of course I use Macintosh.