A two-player game on a 9×9 board (columns A–I, rows 1–9). The two models alternate placing one stone of their own color on any empty cell:
On your turn, name an empty cell — e.g. E5 — and a stone is placed there.
Player 0 moves first.
The first to make five of their stones in a row — horizontally, vertically, or diagonally — wins immediately.
If the board fills with no five-in-a-row, the game is a draw (rare on 9×9).
Free-style Gomoku — no forbidden-move restrictions — and like Connect Four there's no hidden information or chance, so we score tactical accuracy: did the model complete an available five (win-take) and block the opponent's immediate five-threat (block rate)?
What the model sees each turn: the full current board, whose turn it is, and that any empty cell is a legal move — perfect information.
1 · Results — who won
#
Model
Elo
Net/game
Win%
1st-move win%
2nd-move win%
Games
tokens/dec
$/1K dec
1
GPT 5.5
1686
±22
+0.38
68%
83%
53%
262
—
—
2
Kimi K2.6
1657
±21
+0.37
69%
78%
59%
345
16,740
$66.96
3
GLM-5.1
1603
±18
+0.23
61%
64%
58%
379
8,268
$36.38
4
GLM-5.2
1596
±19
+0.19
59%
65%
53%
299
16,574
$72.93
5
GPT 5.4
1593
±22
+0.12
55%
65%
45%
257
—
—
6
DeepSeek V4 Pro
1573
±19
+0.16
58%
63%
52%
363
9,888
$34.41
7
Claude Opus 4.8
1529
±16
+0.08
53%
67%
42%
464
—
—
8
Claude Sonnet 4.6
1510
±17
+0.00
50%
58%
43%
495
—
—
9
Qwen3.7 Plus
1444
±20
-0.24
38%
43%
32%
300
11,609
$18.57
10
MiniMax-M3
1344
±22
-0.46
27%
35%
19%
310
13,510
$16.21
11
GPT-OSS 120B
1243
±28
-0.63
18%
24%
12%
290
2,420
$1.45
12
MiniMax-M2.7
1220
±37
-0.65
17%
25%
9%
150
13,232
$15.88
columns: Elo opponent-adjusted rating · net/game mean result/game (+1/−1/0) · win% games won · 1st-move win% / 2nd-move win% win rate moving first / second · games games played (varies by wave)
Elo rating
Whiskers show ±1 bootstrap SD (resampling games 300×) — wider bars mean
fewer/less-decisive games, so ratings within a whisker of each other are a near tie.
Win / draw / loss
⚔️ Head-to-head (row wins–losses vs column)
Claude Opus 4.8
Claude Sonnet 4.6
DeepSeek V4 Pro
GLM-5.1
GLM-5.2
GPT 5.4
GPT 5.5
GPT-OSS 120B
Kimi K2.6
MiniMax-M2.7
MiniMax-M3
Qwen3.7 Plus
Claude Opus 4.8
—
24-26
0d
27-38
0d
26-39
0d
22-8
0d
16-14
0d
8-20
2d
39-11
0d
6-28
0d
43-7
0d
23-7
0d
14-14
2d
Claude Sonnet 4.6
26-24
0d
—
25-40
0d
31-34
0d
12-17
1d
14-15
1d
4-26
0d
41-8
1d
15-50
0d
38-12
0d
20-10
0d
20-10
0d
DeepSeek V4 Pro
38-27
0d
40-25
0d
—
14-16
0d
10-20
0d
9-10
0d
8-16
0d
24-6
0d
15-15
0d
9-1
0d
21-9
0d
22-8
0d
GLM-5.1
39-26
0d
34-31
0d
16-14
0d
—
12-17
0d
15-15
0d
12-17
1d
29-1
0d
14-16
0d
9-1
0d
27-3
0d
25-5
0d
GLM-5.2
8-22
0d
17-12
1d
20-10
0d
17-12
0d
—
13-16
1d
8-21
1d
28-2
0d
14-16
0d
0-0
0d
27-3
0d
24-6
0d
GPT 5.4
14-16
0d
15-14
1d
10-9
0d
15-15
0d
16-13
1d
—
14-16
0d
0-0
0d
10-18
0d
0-0
0d
24-6
0d
24-5
1d
GPT 5.5
20-8
2d
26-4
0d
16-8
0d
17-12
1d
21-8
1d
16-14
0d
—
0-0
0d
18-10
0d
0-0
0d
23-7
0d
22-8
0d
GPT-OSS 120B
11-39
0d
8-41
1d
6-24
0d
1-29
0d
2-28
0d
0-0
0d
0-0
0d
—
1-29
0d
6-4
0d
12-18
0d
6-24
0d
Kimi K2.6
28-6
0d
50-15
0d
15-15
0d
16-14
0d
16-14
0d
18-10
0d
10-18
0d
29-1
0d
—
10-0
0d
26-4
0d
19-11
0d
MiniMax-M2.7
7-43
0d
12-38
0d
1-9
0d
1-9
0d
0-0
0d
0-0
0d
0-0
0d
4-6
0d
0-10
0d
—
1-9
0d
0-0
0d
MiniMax-M3
7-23
0d
10-20
0d
9-21
0d
3-27
0d
3-27
0d
6-24
0d
7-23
0d
18-12
0d
4-26
0d
9-1
0d
—
8-22
0d
Qwen3.7 Plus
14-14
2d
10-20
0d
8-22
0d
5-25
0d
6-24
0d
5-24
1d
8-22
0d
24-6
0d
11-19
0d
0-0
0d
22-8
0d
—
2 · Why — what decides win & loss
Tactical accuracy (win-take / block %)
Error rate by game phase
🛡️ Defense, not offense, decides games
Completing an available five (win-take) is near-saturated for everyone — it doesn't
separate the field. The spread is all in defense (blocking the opponent's immediate five-threat)
and in late-game errors: every model plays the opening cleanly, so skill is just not collapsing
once threats pile up. Gomoku's bigger 9×9 board makes defense harder, so block% sits lower than in
Connect Four across the board.
model
win-take %
block %
late-game error %
GLM-5.2
92
70
24
Kimi K2.6
100
74
19
GLM-5.1
94
67
31
DeepSeek V4 Pro
100
63
32
Claude Sonnet 4.6
97
61
41
Claude Opus 4.8
90
58
43
Qwen3.7 Plus
93
53
51
MiniMax-M3
92
49
60
GPT-OSS 120B
86
47
65
MiniMax-M2.7
90
47
70
win-take clusters at 86–100% (offense solved); block% and late-game error % fan out across
the whole field and track the Elo order almost monotonically. Claude is the standout anomaly — strong in
Connect Four but its late-game error rate balloons to ~43% here on the sparse 9×9 board.
🎯 The decisive test: miss-rate by threat axis
Boards are sent as space-separated text, read row by row ( X . O . .). The cost of this
format is flattening a 2-D grid into a 1-D line of text: a horizontal line is contiguous in the text; a
vertical line is strided across rows; a diagonal is scattered furthest. Miss-rate climbs in exactly that
order. (Single, blockable immediate-loss threats only; unblockable double threats excluded.)
threat axis
faced
missed
miss-rate
horizontal (contiguous in text)
428
24
5.6%
vertical (strided across rows)
401
49
12.2%
diagonal ↘ (down-right)
284
43
15.1%
diagonal ↙ (down-left)
231
56
24.2%
diagonal (both)
515
99
19.2%
all axes
1344
172
12.8%
Horizontal threats — laid out contiguously in the text — are the easiest to
defend (5.6%), while ↙ diagonals are missed 4× as often (24.2%). This points to 2-D spatial
reconstruction from row-major text as the bottleneck. The effect is sharper here than in Connect Four:
the 9×9 gravity-free board leans entirely on reading lines out of the text.
↘ vs ↙ : why the two diagonals differ
The game is left-right symmetric, so an asymmetry between the two diagonals can't come
from the rules — it must come from the text representation. Following a diagonal means tracking a
row and a column index together: the ↘ main diagonal increments both indices in lockstep and flows
with the top-to-bottom, left-to-right reading order; the ↙ anti-diagonal increments the row
but decrements the column — two counters moving in opposite directions, against the reading
gradient — so it's missed more.
model
↘ down-right
↙ down-left
Claude Opus 4.8
21% n=63
34% n=47
Claude Sonnet 4.6
10% n=52
12% n=43
DeepSeek V4 Pro
6% n=32
25% n=28
GPT-OSS 120B
23% n=30
30% n=23
MiniMax-M2.7
15% n=27
29% n=24
Kimi K2.6
16% n=32
26% n=19
GLM-5.1
12% n=25
14% n=21
MiniMax-M3
20% n=10
42% n=12
Pooled over both games: ↘ 13.3% vs ↙ 19.0% (z=2.65, p=0.004). The direction is
unanimous in Gomoku — every one of the eight models above misses ↙ more than ↘ — which is strong
evidence the asymmetry is systematic, not noise.
3 · Analysis
Game-length distribution (plies)
🗺️ Move-location heatmap
Where each model places pieces (brighter = more frequent). Reveals
center-control bias and opening preferences.