Intermediate Gomoku: Read the Position Before You Move
These two constructed practice games use this site’s casual exact-five rule on a 15×15 board. They are short on purpose: you can replay every stone in the local two-player board and pause before the losing choice. They are teaching examples, not tournament records or proofs about formal Renju.
Coordinates use A–O left to right and 1–15 bottom to top. Black moves on odd numbers; White moves on even numbers. A move list is complete through the winning move, so you can verify that no earlier move already made five.
The five-question scan
- What exact win condition applies? Here it is five in a row, not an overline.
- Can I complete five on this turn? Check both ends of each line.
- Can my opponent complete five on their next turn? Mark every immediate winning point.
- Can either side create an open four? A single block cannot cover two open winning ends.
- If I choose an attacking move, what is the opponent’s strongest reply?
Practice game 1: Both players extend, Black moves first
Complete record: 1 B H8 · 2 W H9 · 3 B I8 · 4 W I9 · 5 B J8 · 6 W J9 · 7 B K8 · 8 W K9 · 9 B L8 (Black wins).
After move 5, Black has H8–J8 and White has H9–I9. It is White’s turn. The tempting move is J9: it gives White three, but it allows Black’s next move at K8 to make an open four.
If White plays G8 or K8 on move 6, the immediate two-ended four shown below does not arise on move 7. That does not prove either defense wins; it only prevents this short forcing sequence. In the recorded line White instead plays J9.
At move 8 White could occupy G8 or L8, but Black would then complete five at the other end on move 9. White’s actual K9 builds a four on row 9 but does not win immediately. Black plays L8 and finishes H8–L8. The turning point was White’s move 6, not the final move.
Every legal reply to Black 7 K8
There are 218 empty intersections. The response table groups every legal White move by its effect on the two immediate winning ends. It is a one-turn result for this recorded board; it does not prove the earlier opening was forced.
| White move 8 | Legal moves | Black move 9 |
|---|---|---|
| G8 | 1 | L8 makes H8–L8 |
| L8 | 1 | G8 makes G8–K8 |
| Any other empty intersection | 216 | Either G8 or L8 makes five |
We checked all 218 replies with this site's exact-five game engine. None gives White an immediate five on move 8, and Black has a legal winning completion after each one.
Try the alternative White move 6 at G8, then at K8. Record Black’s best reply in each branch; the example does not claim a complete solution to either branch.
Practice game 2: Black overlooks White’s vertical line
Complete record: 1 B H8 · 2 W I8 · 3 B G8 · 4 W I9 · 5 B G9 · 6 W I10 · 7 B H9 · 8 W I11 · 9 B F8 · 10 W I12 (White wins).
After move 6, White owns I8, I9, and I10. Black’s stones around H8 and G8 look connected, but Black has no immediate win. Before playing H9 on move 7, Black should inspect I7 and I11—the two ways White can extend that column.
Black plays H9. White then plays I11, making a straight four I8–I11 with I7 and I12 open. The move does not yet make five, but it gives White two winning points on the following turn.
Black’s F8 at move 9 ignores both points, so White wins at I12. Even if Black had played I7 or I12 at move 9, White could have used the other end. The useful decision was earlier: at move 7, block a growth point or calculate a genuine counter-threat before playing H9. This example does not assert that a particular move 7 saves the full game.
Every legal reply to White 8 I11
Black has 217 legal intersections. No move completes a Black five immediately on this board. Blocking either end of White's four leaves the other end free.
| Black move 9 | Legal moves | White move 10 |
|---|---|---|
| I7 | 1 | I12 makes I8–I12 |
| I12 | 1 | I7 makes I7–I11 |
| Any other empty intersection | 215 | Either I7 or I12 makes five |
The exact-five engine checked all 217 Black replies and found a legal White completion after each one. This establishes the immediate result after move 8, not whether Black had a defense on move 7.
Replay the move before the open four
The two losses look inevitable in their final diagrams, but a useful review starts one turn earlier. Change only the indicated defensive move, keep the earlier record unchanged, and compare the immediate winning points. This is a test of one short branch, not a claim that the alternative wins the whole game.
Game 1: replace White 6 J9
After Black 5 J8, try White 6 G8 instead of J9. If Black 7 K8, the four H8–K8 now has White at G8 on its left. White 8 can occupy L8, the remaining immediate winning end. Black has no row-8 five on move 9 in this branch. Repeat with White 6 K8 to see why the direction of Black's next extension changes. These moves address this particular horizontal threat; the rest of the board still requires analysis.
Game 2: replace Black 7 H9
After White 6 I10, try Black 7 I11 instead of H9. That occupies one growth point of White's I8–I10 column. White 8 can still play I7, making four from I7 through I10, but now only I6 remains an immediate fifth-stone point because Black holds I11. Black 9 can occupy I6. The resulting position is not solved; it simply shows how an earlier block can prevent the recorded two-ended four.
When you review your own game, write the first move where an opponent could build an open four. Then test at least one defense at that earlier turn. A final move that merely blocks one of two winning ends is often too late; the board diagrams above show exactly when the second end appeared.
What these games do and do not prove
A straight four with two legal winning ends is decisive if the opponent has no immediate counter-win or other rule-specific escape. A three is only a candidate threat: you must inspect the full board, both possible extensions, and the opponent’s replies. Terms such as VCF and VCT describe sequences, not a shortcut around that analysis.
For formal Renju, Black’s forbidden moves and the opening procedure change the legal branches. Consult the RIF rules before applying a casual exact-five diagram to tournament play. The advanced study page gives a checklist for checking a claimed forced line.