[{"data":1,"prerenderedAt":29},["ShallowReactive",2],{"i-lucide:grip":3,"i-lucide:chevron-right":8,"i-lucide:moon":10,"i-lucide:sun":12,"i-lucide:languages":14,"i-lucide:chevron-down":16,"i-lucide:shield-check":18,"i-lucide:mail":20,"blog-body-gomoku-renju-forbidden-moves-en":22,"i-lucide:cpu":23,"i-lucide:gamepad-2":25,"i-lucide:star":27},{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":7},0,24,false,"\u003Cg fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\">\u003Ccircle cx=\"12\" cy=\"5\" r=\"1\"\u002F>\u003Ccircle cx=\"19\" cy=\"5\" r=\"1\"\u002F>\u003Ccircle cx=\"5\" cy=\"5\" r=\"1\"\u002F>\u003Ccircle cx=\"12\" cy=\"12\" r=\"1\"\u002F>\u003Ccircle cx=\"19\" cy=\"12\" r=\"1\"\u002F>\u003Ccircle cx=\"5\" cy=\"12\" r=\"1\"\u002F>\u003Ccircle cx=\"12\" cy=\"19\" r=\"1\"\u002F>\u003Ccircle cx=\"19\" cy=\"19\" r=\"1\"\u002F>\u003Ccircle cx=\"5\" cy=\"19\" r=\"1\"\u002F>\u003C\u002Fg>",{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":9},"\u003Cpath fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"m9 18l6-6l-6-6\"\u002F>",{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":11},"\u003Cpath fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"M20.985 12.486a9 9 0 1 1-9.473-9.472c.405-.022.617.46.402.803a6 6 0 0 0 8.268 8.268c.344-.215.825-.004.803.401\"\u002F>",{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":13},"\u003Cg fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\">\u003Ccircle cx=\"12\" cy=\"12\" r=\"4\"\u002F>\u003Cpath d=\"M12 2v2m0 16v2M4.93 4.93l1.41 1.41m11.32 11.32l1.41 1.41M2 12h2m16 0h2M6.34 17.66l-1.41 1.41M19.07 4.93l-1.41 1.41\"\u002F>\u003C\u002Fg>",{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":15},"\u003Cpath fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"m5 8l6 6m-7 0l6-6l2-3M2 5h12M7 2h1m14 20l-5-10l-5 10m2-4h6\"\u002F>",{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":17},"\u003Cpath fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"m6 9l6 6l6-6\"\u002F>",{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":19},"\u003Cg fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\">\u003Cpath d=\"M20 13c0 5-3.5 7.5-7.66 8.95a1 1 0 0 1-.67-.01C7.5 20.5 4 18 4 13V6a1 1 0 0 1 1-1c2 0 4.5-1.2 6.24-2.72a1.17 1.17 0 0 1 1.52 0C14.51 3.81 17 5 19 5a1 1 0 0 1 1 1z\"\u002F>\u003Cpath d=\"m9 12l2 2l4-4\"\u002F>\u003C\u002Fg>",{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":21},"\u003Cg fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\">\u003Cpath d=\"m22 7l-8.991 5.727a2 2 0 0 1-2.009 0L2 7\"\u002F>\u003Crect width=\"20\" height=\"16\" x=\"2\" y=\"4\" rx=\"2\"\u002F>\u003C\u002Fg>","\u003Cblockquote>\n\u003Cp>\u003Cstrong>Renju forbids\u003C\u002Fstrong> apply only to Black: if one move simultaneously creates two open threes (double-three), two fours (double-four), or a line of six or more (overline), that point is forbidden—playing there loses immediately. An exact five-in-a-row is still a legal win. White is not bound by these three fouls.\u003C\u002Fp>\n\u003C\u002Fblockquote>\n\u003Cp>\u003Cimg src=\"\u002Fblog\u002Fgomoku-renju-forbidden-moves\u002Fcover.webp\" alt=\"Red X marks on a board illustrating Black’s forbidden points\">\u003C\u002Fp>\n\u003Ch2>Why Do Freestyle Gomoku and Renju Bring Up “Forbidden Moves”?\u003C\u002Fh2>\n\u003Cp>Freestyle Gomoku is minimal: players alternate stones; first to get five in a row horizontally, vertically, or diagonally wins; Black moves first; \u003Cstrong>there are no forbids\u003C\u002Fstrong>. At high level on a large enough board, Black’s first-move edge can approach a forced win. Competitive Renju therefore adds \u003Cstrong>forbidden moves\u003C\u002Fstrong> for Black to pull that advantage back toward fairness.\u003C\u002Fp>\n\u003Cp>A “forbid” is not “you cannot click the intersection.” It means: \u003Cstrong>if Black places a stone there, Black loses at once\u003C\u002Fstrong> (White wins). Software often marks current forbidden points with a red X; Black may still mis-click—then the UI reports a foul and ends the game.\u003C\u002Fp>\n\u003Ctable>\n\u003Cthead>\n\u003Ctr>\n\u003Cth>Rules\u003C\u002Fth>\n\u003Cth>Black forbids\u003C\u002Fth>\n\u003Cth>White forbids\u003C\u002Fth>\n\u003Cth>Typical use\u003C\u002Fth>\n\u003C\u002Ftr>\n\u003C\u002Fthead>\n\u003Ctbody>\n\u003Ctr>\n\u003Ctd>Freestyle Gomoku\u003C\u002Ftd>\n\u003Ctd>None\u003C\u002Ftd>\n\u003Ctd>None\u003C\u002Ftd>\n\u003Ctd>Casual, beginners, blitz\u003C\u002Ftd>\n\u003C\u002Ftr>\n\u003Ctr>\n\u003Ctd>Renju\u003C\u002Ftd>\n\u003Ctd>Double-three \u002F double-four \u002F overline\u003C\u002Ftd>\n\u003Ctd>None\u003C\u002Ftd>\n\u003Ctd>Competition, training, fairer matches\u003C\u002Ftd>\n\u003C\u002Ftr>\n\u003Ctr>\n\u003Ctd>Local “pseudo-Renju” variants\u003C\u002Ftd>\n\u003Ctd>Details may differ\u003C\u002Ftd>\n\u003Ctd>Usually none\u003C\u002Ftd>\n\u003Ctd>Agree on the rulebook before kickoff\u003C\u002Ftd>\n\u003C\u002Ftr>\n\u003C\u002Ftbody>\n\u003C\u002Ftable>\n\u003Cp>International Renju uses a \u003Cstrong>15×15\u003C\u002Fstrong> board; practicing forbid shapes on \u003Cstrong>13×13\u003C\u002Fstrong> is fine for casual study—the board is tighter, so shapes appear earlier.\u003C\u002Fp>\n\u003Ch2>What Is a Double-Three? One Move, Two Open Threes\u003C\u002Fh2>\n\u003Cp>A double-three means Black \u003Cstrong>creates two open threes with a single placement\u003C\u002Fstrong>. An open three, intuitively, is a three that can become a clear “four” threat (straight or broken four) on the next move, with openness meeting Renju’s definition. When \u003Cstrong>the same move\u003C\u002Fstrong> births two such threes, it is a foul.\u003C\u002Fp>\n\u003Cp>The diagram below is a simplified teaching figure: blue and orange bands mark the two forming threes; the crossing empty point is marked with a red X—if Black plays there, one move completes both a horizontal and a vertical open three.\u003C\u002Fp>\n\u003Cp>\u003Cimg src=\"\u002Fblog\u002Fgomoku-renju-forbidden-moves\u002Fdouble-three.webp\" alt=\"Double-three: the red X creates horizontal and vertical open threes at once\" style=\"width:70%\">\u003C\u002Fp>\n\u003Cp>When reading the figure, keep three points in mind:\u003C\u002Fp>\n\u003Col>\n\u003Cli>\u003Cstrong>Count open threes, not “any three stones”\u003C\u002Fstrong>: a three blocked by White that cannot become a four usually does not count;\u003C\u002Fli>\n\u003Cli>\u003Cstrong>Both must come from the same move\u003C\u002Fstrong>: having one open three already, then making another later, is generally not a double-three;\u003C\u002Fli>\n\u003Cli>\u003Cstrong>White may deliberately make double threes\u003C\u002Fstrong>: forbids punish Black only; White attacking with two open threes is legal.\u003C\u002Fli>\n\u003C\u002Fol>\n\u003Cp>In real games, double-threes often sit at “diagonal bloom” or right-angle crossings—one point controlling two lines—which is why UIs like crossing highlights.\u003C\u002Fp>\n\u003Ch2>What Is a Double-Four? One Move, Two Fours\u003C\u002Fh2>\n\u003Cp>A double-four means Black \u003Cstrong>creates two “fours” with a single placement\u003C\u002Fstrong> (open fours, straight fours, etc., as defined by the rulebook). A four is closer to winning: the opponent usually must answer. Creating two fours at once means White cannot block both, so Renju forbids Black from doing it.\u003C\u002Fp>\n\u003Cp>In the figure, three stones sit horizontally to the left and three vertically above; the crossing empty point, if filled by Black, makes two fours at once (blue\u002Forange bands).\u003C\u002Fp>\n\u003Cp>\u003Cimg src=\"\u002Fblog\u002Fgomoku-renju-forbidden-moves\u002Fdouble-four.webp\" alt=\"Double-four: the red X creates horizontal and vertical fours at once\" style=\"width:70%\">\u003C\u002Fp>\n\u003Cp>Compare with double-three:\u003C\u002Fp>\n\u003Ctable>\n\u003Cthead>\n\u003Ctr>\n\u003Cth>Foul\u003C\u002Fth>\n\u003Cth>One move creates\u003C\u002Fth>\n\u003Cth>Threat level\u003C\u002Fth>\n\u003Cth>Common beginner mix-up\u003C\u002Fth>\n\u003C\u002Ftr>\n\u003C\u002Fthead>\n\u003Ctbody>\n\u003Ctr>\n\u003Ctd>Double-three\u003C\u002Ftd>\n\u003Ctd>Two open threes\u003C\u002Ftd>\n\u003Ctd>One more move to reach a “four”\u003C\u002Ftd>\n\u003Ctd>Counting dead or fake threes\u003C\u002Ftd>\n\u003C\u002Ftr>\n\u003Ctr>\n\u003Ctd>Double-four\u003C\u002Ftd>\n\u003Ctd>Two fours\u003C\u002Ftd>\n\u003Ctd>Already forcing replies\u003C\u002Ftd>\n\u003Ctd>Calling a “four-three” a double-four\u003C\u002Ftd>\n\u003C\u002Ftr>\n\u003Ctr>\n\u003Ctd>Overline\u003C\u002Ftd>\n\u003Ctd>Six or more in a row\u003C\u002Ftd>\n\u003Ctd>Immediate foul\u003C\u002Ftd>\n\u003Ctd>Thinking “longer is better”\u003C\u002Ftd>\n\u003C\u002Ftr>\n\u003C\u002Ftbody>\n\u003C\u002Ftable>\n\u003Cp>A \u003Cstrong>four-three\u003C\u002Fstrong>—one four plus one open three in a single move—is \u003Cstrong>usually legal\u003C\u002Fstrong> in Renju (follow your rulebook) and still very strong; do not conflate it with double-four or double-three.\u003C\u002Fp>\n\u003Ch2>How Does Overline Differ From an Exact Five?\u003C\u002Fh2>\n\u003Cp>An overline foul means Black’s move creates a line of \u003Cstrong>six or longer\u003C\u002Fstrong> and loses. Freestyle habits of “connect as long as possible” make it easy to overshoot once forbids are on.\u003C\u002Fp>\n\u003Cp>The figure below: before the move the shape is “four stones + gap + one stone” (longest run is four—no five-in-a-row win yet). Filling the gap at the red X makes six at once—that is the overline foul, not “already five, then one more beyond.”\u003C\u002Fp>\n\u003Cp>\u003Cimg src=\"\u002Fblog\u002Fgomoku-renju-forbidden-moves\u002Foverline.webp\" alt=\"Overline: filling the gap between four stones and one stone makes six—a foul\" style=\"width:70%\">\u003C\u002Fp>\n\u003Cp>Contrast with the next figure: in the same direction, completing exactly five (green ring) is a \u003Cstrong>legal win\u003C\u002Fstrong>.\u003C\u002Fp>\n\u003Cp>\u003Cimg src=\"\u002Fblog\u002Fgomoku-renju-forbidden-moves\u002Fexact-five.webp\" alt=\"Exact five-in-a-row: a legal win\" style=\"width:70%\">\u003C\u002Fp>\n\u003Cp>A short mnemonic: \u003Cstrong>Black wants exactly five; one more and it backfires. White has no overline foul\u003C\u002Fstrong>—in Renju White already wins with five, so longer lines are usually moot. Practice Black’s “stop cleanly” habit: count the length after the candidate move, not only whether White is blocked.\u003C\u002Fp>\n\u003Ch2>How Do You Tell If a Point Is Forbidden?\u003C\u002Fh2>\n\u003Cp>Use a fixed three-step check instead of memorizing every shape:\u003C\u002Fp>\n\u003Col>\n\u003Cli>\u003Cstrong>Imagine Black plays on that empty point\u003C\u002Fstrong> (mental trial only);\u003C\u002Fli>\n\u003Cli>\u003Cstrong>Count separately\u003C\u002Fstrong>: ≥2 open threes? ≥2 fours? a run of length ≥6?;\u003C\u002Fli>\n\u003Cli>\u003Cstrong>Any yes → forbidden\u003C\u002Fstrong>. As a learner you need not enumerate every rare pattern: modern Renju engines mark Black’s current forbidden points. What you train is \u003Cstrong>decision-making when you see the red X\u003C\u002Fstrong>—steer the attack around forbids, or use forbid structure to push Black onto second-best points.\u003C\u002Fli>\n\u003C\u002Fol>\n\u003Cp>One easy boundary: \u003Cstrong>an exact five is a legal Black win\u003C\u002Fstrong>; if the same move makes six or more, it is an overline foul. When unsure, trust the engine marks and the rulebook for your game.\u003C\u002Fp>\n\u003Ch2>How Can You Practice These Shapes in the Browser?\u003C\u002Fh2>\n\u003Cp>To turn diagram red X’s into instincts you can dodge—and use—open Renju mode on the site’s Gomoku page: go to \u003Ca href=\"\u002Fgames\u002Fgomoku\u002F\">online Gomoku\u003C\u002Fa>, set difficulty to Heaven, and turn on \u003Cstrong>Renju forbids\u003C\u002Fstrong> (13×13 or 15×15). When it is Black’s turn, forbidden points are marked; if you play Black and hit one, you get a foul notice and lose—handy for checking the three shapes above.\u003C\u002Fp>\n\u003Cp>Suggested practice order:\u003C\u002Fp>\n\u003Col>\n\u003Cli>\u003Cstrong>Play White first\u003C\u002Fstrong>: let the engine take Black; watch how it avoids red X’s and how forbid structure pressures you;\u003C\u002Fli>\n\u003Cli>\u003Cstrong>Then play Black\u003C\u002Fstrong>: in the early–middle game, deliberately watch the marks and force yourself to find attacking points that are not fouls;\u003C\u002Fli>\n\u003Cli>\u003Cstrong>Shape drills\u003C\u002Fstrong>: set up double-three \u002F double-four \u002F overline skeletons, check whether engine marks match your expectation, then try legal mates that are “one intersection off” from a foul.\u003C\u002Fli>\n\u003C\u002Fol>\n\u003Cp>For casual freestyle, turn the switch off—rules return to no-forbid Gomoku without affecting other difficulties.\u003C\u002Fp>\n\u003Ch2>Takeaways: Three Sentences Are Enough to Start\u003C\u002Fh2>\n\u003Col>\n\u003Cli>\u003Cstrong>Forbids punish Black only\u003C\u002Fstrong>: double-three, double-four, overline; White has none of these three.\u003C\u002Fli>\n\u003Cli>\u003Cstrong>Core intuition\u003C\u002Fstrong>: Black may not create two unstoppable killing structures in one move, nor make six or more in a row.\u003C\u002Fli>\n\u003Cli>\u003Cstrong>Five wins, six fouls\u003C\u002Fstrong>: count length when finishing; when unsure, read the red X’s and practice in \u003Ca href=\"\u002Fgames\u002Fgomoku\u002F\">Gomoku Renju mode\u003C\u002Fa>.\u003C\u002Fli>\n\u003C\u002Fol>\n",{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":24},"\u003Cg fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\">\u003Cpath d=\"M12 20v2m0-20v2m5 16v2m0-20v2M2 12h2m-2 5h2M2 7h2m16 5h2m-2 5h2M20 7h2M7 20v2M7 2v2\"\u002F>\u003Crect width=\"16\" height=\"16\" x=\"4\" y=\"4\" rx=\"2\"\u002F>\u003Crect width=\"8\" height=\"8\" x=\"8\" y=\"8\" rx=\"1\"\u002F>\u003C\u002Fg>",{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":26},"\u003Cpath fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"M6 11h4M8 9v4m7-1h.01M18 10h.01m-.69-5H6.68a4 4 0 0 0-3.978 3.59l-.017.152C2.604 9.416 2 14.456 2 16a3 3 0 0 0 3 3c1 0 1.5-.5 2-1l1.414-1.414A2 2 0 0 1 9.828 16h4.344a2 2 0 0 1 1.414.586L17 18c.5.5 1 1 2 1a3 3 0 0 0 3-3c0-1.545-.604-6.584-.685-7.258q-.01-.075-.017-.151A4 4 0 0 0 17.32 5\"\u002F>",{"left":4,"top":4,"width":5,"height":5,"rotate":4,"vFlip":6,"hFlip":6,"body":28},"\u003Cpath fill=\"none\" stroke=\"currentColor\" stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"M11.525 2.295a.53.53 0 0 1 .95 0l2.31 4.679a2.12 2.12 0 0 0 1.595 1.16l5.166.756a.53.53 0 0 1 .294.904l-3.736 3.638a2.12 2.12 0 0 0-.611 1.878l.882 5.14a.53.53 0 0 1-.771.56l-4.618-2.428a2.12 2.12 0 0 0-1.973 0L6.396 21.01a.53.53 0 0 1-.77-.56l.881-5.139a2.12 2.12 0 0 0-.611-1.879L2.16 9.795a.53.53 0 0 1 .294-.906l5.165-.755a2.12 2.12 0 0 0 1.597-1.16z\"\u002F>",1786455161864]