I always have a hard time keeping moyos from invaders. This game was probably my most successful attempt at building a moyo, but I’m not sure how well I handled the invasion. Could anyone please have a look at my review? Many thanks in advance!
Here are some thoughts:
I’m not substantially stronger than you, so take them with a grain of salt. I think my biggest takeaway, though, would be that you seem hesitant to sacrifice stones. You had a few opportunities to give up a stone or two to clarify the middle a bit, but held on to everything and things got complicated. Figure that your opponent will get something. Your goal is to give them a very small something, rather than to hold on to everything.
I added a couple variations.
K8 is a very nice counter-attack.
As you found out, you can’t be very aggressive when your groups have weaknesses. Instead of trying to kill, another strategy would be to chase white, cancelling out both moyos. This might cost you your 4 stones.
Thank you very much for your replies and for the variations - much appreciated. I definitely should have let go of the two stones at N14-O-14 for a stronger middle. Also, thank you for the variation at the bottom left - makes more sense than the one I played.
My main problem with moyos is that I never know whether to try to seal them or to invite the opponent in. I often read that, when you create thickness on one side (like my wall on the right), you should not simply try to build a box on the left, but rather use it to attack the opposite side, letting your opponent come in to your moyo and then seal him in. Is that always the case, or do you often just box yourself in to make territory?
Thanks!
That’s a pro level question 
I’d say that it’s more your opponent’s decision and you need to plan for both.
My personal feeling is that beginners tend to seal in too early, while stronger players count too much on the opponent’s invasion.
I think we agreed that what you had was not true thickness, because white had several threats against your right side stones. So you’ll need to adjust your strategy accordingly.
It’s not easy to assess thickness, AI taught us that even 9p had it wrong! And one move can make a big difference (see my peep variation).
Ask yourself this question: once I have attacked my opponent, what do I get in return?
If you kill, fine, that’s a lot of points. If you don’t, then what have you accomplished? Did you secure points? Build useful thickness?
I still remember a game, years ago, where my opponent sealed me in, forcing me to live small. He couldn’t understand why he lost the game, having “played by the book”. The thing is, the impressive thickness he had built proved useless because the rest of the board was already secured.
Thank you for your comments, and sorry for the late reply - been on holiday. That’s all very useful.
So basically if in doubt, try to seal the moyo rather than attacking? The larger the moyo, the harder it is to see whether I can do anything more useful than actually sealing it. Plus, I’m not always entirely sure whether I will be able to use my influence and/or thickness…
Having doubts is normal. Ask yourself those questions in your upcoming games and see where it takes you. Also, I would recommend to look at pro games that have similar moyo sizes and check what happens.
Not necessarily. Even if you have a doubt, try the most appealing option.
Really? I would think the other way around: the larger the moyo, the harder it is to seal, and the more you should find another purpose. But again, don’t expect a straightforward rule.
And btw it’s not necessarily one vs. the other. Often while you attack you’ll seal part of the moyo.
So maybe this is where you could improve the most. A moyo doesn’t make sense without a plan.
From your comments, it seems to me that you are only looking at your own stones. Start looking at the whole game!
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