24. The Decline of Cosmic Go
'It's Hard to Convert a Moyo into Territory.'

by Richard Bozulich
March 20, 2024

During the 1980s and 90s, Cosmic Go was quite popular among amateurs and even among some pros. It was a strategy in which a player would set up a large-scale moyo and pay little attention to securing territory, at least in the opening and early middle-game. Its popularity was due to Takemiya Masaki 9-dan who pulled off some spectacular wins using it. Other players, such as Sonoda Yuichi 9-dan, were also adherents of this strategy and scored some impressive wins.

However, with the advent of AI, large-scale moyo strategies have fallen out of favor and pros prefer to play a more territory-oriented game, just as the go-playing AI programs do. As ShibanoToramaru Meijin emphasizes throughout his two books on go and AI, Fuseki Revolution and Joseki Revolution, 'It's hard to convert a moyo into territory.'

In spite of this swing in popular opinion among pros, we still see games in which one player allows his opponent to take a sizeable lead in territory, hoping he can overcome this lead by using the influence of his moyo to secure even more territory. Here is an example from a recent professional game that illustrates how hard it is to win by employing this strategy.

Highlight Diagram
Highlight Diagram
This position arose in a game between Tanaka Yuki 2-dan (White) and Nishi Takenobu 5-dan. It was played in the second round (D-block) of the 33rd Ryusei tournament on November 5, 2023.

White has built an enormous wall facing the right, stretching from the bottom left to the top right. Black, however, has secured quite a bit of territory. White is going to have to use the influence of his wall to build a moyo that will be greater than the territory Black has so far amassed. Where would you play?

Figure 1 (1–65)
Figure 1 (1–65)
Here are the moves that led up to the position in the highlight diagram. The move-by-move game record can be found at Tanaka vs. Nishi

Dia. 1
Dia. 1. Wishful thinking
White 1 looks like a strong move. It expands White's moyo and threatens to stop Black from making territory on the right side. If Black obediently responds by expanding his territory with 2, White will play 3. If both sides persist up to 7, White's moyo is much bigger than Black's territory. Of course Black might be able to live inside White's moyo, but, instead of 7, White could play a move reinforcing his position there. In any case, for White to expect this result would be wishful thinking.

Dia. 2
Dia. 2. Fighting back
The correct way to answer White 1 is with a shoulder hit at 2. This stops White from expanding his moyo to any great extent.

Figure 1 (1–5)
Figure 1 (1–5). Best guess?
In positions such as the one here, it is very hard to determine which is the best point to expand White's moyo. White 1 is probably Tanaka's best guess — staking out a moyo on a smaller, but more manageable scale.

Black starts his invasion by attaching with 2, then jumping to 4.

White 5 seems to be an innocuous forcing move, but Black has to be careful how he answers.

After Black 4 —

Dia. 3
Dia. 3. White's attack fails.
White would like to attack Black with 1, but, after the moves to 8, Black has linked up with his stones in the corner and White's moyo has been substantially erased. (White can't cut at 'a' because of the marked stone.)

So what about White 5 in Figure 1?

Dia. 4
Dia. 4. Black is trapped.
When White peeps with 1, he is hoping that Black answers with the standard connection of 2. In that case, the attack of White 3 to 9 traps the black stones inside White's moyo.

Therefore —

Figure 2 (6–8).
Figure 2 (6–8). The key point
Black pushes up with 6 and White plays a hane with 7. Black now plays on the key point of 8, pulling his marked stone out of White's sphere of influence.

Instead of 8 —

Dia. 5
Dia. 5. Double atari
If Black plays a hane with 1, White will push in with 2, then play a two-step hane with 4. After Black 9, White plays a double atari with 10. No matter how Black answers, he can't get a good result.

Instead of 7 —


Dia. 6
Dia. 6. White secures his moyo.
Black is forced to extend to 7. If White pushes with 8 and 10, Black stakes out a large territory on the right side with 11. In compensation, White secures his moyo.

Dia. 7
Dia. 7. Capturing the corner
After Black 8 in Figure 2, White could capture the corner by cutting through with 1 and 3, then playing 5 and 7. However, Black has staked out a large-scale moyo on the right side with 8 and White's moyo to the left no longer looks so formidable.

Figure 3 (9—18)
Figure 3 (9–18).
After Black 8 in Figure 2, White cuts through with 9 and 11, then ataries with 13, forcing Black to capture with 14. White now ataries with 15. This seems like a strange move. Because of the marked stone, the ladder doesn't work, yet Black ignores it and jumps to 16, allowing White to capture two stones with 17. Black now plays 18, establishing a position inside White's moyo.

Dia. 8
Dia. 8. Casting a net
After White 15 in Figure 3, if Black tries to rescue his two stones by running away with 1, he will soon realize that White was not thinking about a ladder. Rather, it was the net tesuji of 2 that he had in mind. After 6, White has isolated the three black stones inside his moyo.

Dia. 8
Figure 4 (19–52)
White plays on the key point of 19. After the skirmish to 31, White has secured some profit. Note that Black can't save his two-stone group at 26. If he plays at 'a', White will run way with 'b'. Still, after Black 32, AI evaluates the game as favorable for Black. Note that Black's six stones in the center neutralize White's thick position below.

White invades and lives in the lower right corner with 33 to 49, but in doing so he leaves Black with a thick position on the outside. Black now pushes up and cuts with 50 and 52. Black dominates the center and White has a lost game.

The result:
205 moves.
Black (Nishi Takenobu) won by resignation.

The move-by-move game record can be found at Tanaka vs. Nishi