Reviewed 2026-09-24

Advanced Gomoku Study: Verify Before You Call It Forced

Advanced five-in-a-row study is rigorous analysis, not a larger collection of slogans. A claimed forced win must name the rules, the exact position, the player to move, all legal defenses, and a continuation for each defense. This matters even more when moving between casual Gomoku and formal Renju.

The Verification Standard

  1. Record the full board or a complete move list, plus coordinates and side to move.
  2. State the rule set: board size, exact-five or five-or-more, overline treatment, and any opening restrictions.
  3. List every legal defense, not only the visually obvious block.
  4. Check whether the proposed move is legal under the selected rule set.
  5. Only then label a sequence VCF, VCT, fork, forced win, or draw claim.

Three positions worth checking

These are constructed teaching positions, not complete proofs of a forced win. Coordinates use A–O and rows 1–15. A red ring marks a point to examine; it is not an engine recommendation.

1. The same shape changes with the side to move

A 1 B 2 C 3 D 4 E 5 F 6 G 7 H 8 I 9 J 10 K 11 L 12 M 13 N 14 O 15
If Black moves next, L8 completes Black's five. If White moves next, L9 completes White's five.

A screenshot of this board without “side to move” is insufficient. Both colors have a four. Under casual exact-five, the next player can complete five at the highlighted point. A claim that one side is winning must therefore include whose turn it is.

2. A three is a question, not a solution

A 1 B 2 C 3 D 4 E 5 F 6 G 7 H 8 I 9 J 10 K 11 L 12 M 13 N 14 O 15
Black could extend at either end, but White's response must be analyzed.

The red points are possible extensions for Black. If Black plays K8, White may be too late to stop a two-ended four; if it is White's turn now, White can occupy one of those points first. For a VCF or VCT claim, write the move order and every relevant defensive branch.

Worked branch: two blocks, one result

Rebuild this exact-five practice record: 1 Black H8, 2 White H9, 3 Black I8, 4 White I9, 5 Black J8, 6 White J9, 7 Black K8. White is to move. Black has four from H8 through K8 with G8 and L8 empty. White has three on row 9 but cannot complete five on move 8.

1 2 3 4 5 6 7 A 1 B 2 C 3 D 4 E 5 F 6 G 7 H 8 I 9 J 10 K 11 L 12 M 13 N 14 O 15
The numbered stones make the side to move and both defensive points checkable.
  • If White 8 occupies G8, Black 9 plays L8 and wins with H8–L8.
  • If White 8 occupies L8, Black 9 plays G8 and wins with G8–K8.
  • If White 8 plays elsewhere, both winning points remain; Black can complete five at either one.

That is a complete immediate-win check for this recorded position, not proof that the earlier opening was forced. To claim the whole game was forced from move 1, you would also need to analyze White's alternative moves before move 7.

3. Count the whole line under exact-five rules

A 1 B 2 C 3 D 4 E 5 F 6 G 7 H 8 I 9 J 10 K 11 L 12 M 13 N 14 O 15
Black to move. J8 joins six Black stones from F8 through K8: an overline, not an exact-five win here.

A local scan of four stones beside J8 might say “one move wins.” The complete line says otherwise: J8 would join F8–K8 into six. This site's casual rule does not award a win for an overline. Formal Renju applies its own color-specific rule. Always check the squares immediately beyond a proposed five.

Renju Is Its Own Ruleset

Formal Renju is not simply casual Gomoku with a few added patterns. RIF rules define a 15x15 board, a formal opening procedure, and Black-specific forbidden moves. Black overlines, double-fours, and some double-threes require rule-defined analysis; White is treated differently for overlines. Use the current RIF rules and the regulations for a particular event, rather than applying a simplified online diagram.

The RIF materials distinguish 13 direct and 13 indirect opening patterns within their formal framework. Those labels should not be treated as a universal opening menu for every five-in-a-row app.

Study Methods That Hold Up

Annotated games

Use complete records with rule metadata. Pause before each critical move and write your candidate line before reading commentary.

Reproducible puzzles

Keep the full position and solution tree. Do not rely on coordinate fragments that omit blocking stones.

Error log

Classify mistakes as missed win, missed defense, illegal move, or wrong rule assumption. Revisit the same category deliberately.

What "Solved" Does and Does Not Mean

Published work by Victor Allis on Go-Moku and threat-space search established a first-player win for a defined unrestricted 15x15 setting. That result is not a blanket answer for Renju, all board sizes, every exact-five implementation, or every app. It also does not turn a lightweight browser practice opponent into a solver.

For primary material, consult Allis's work on threat-space search and the source scope directly. The site does not claim a published weak or strong solution for standard Renju.

Using This Site's AI Honestly

The browser AI uses local minimax-style search with configured depths of 1, 2, and 3 for Easy, Medium, and Hard. It is designed for local practice. It does not enforce formal Renju, provide engine evaluations, or establish whether a position is theoretically solved.

Further Reading

Work From Full Positions

Use a local board to recreate a line, then test every defense yourself.

Open Practice Board