constructor(o) {
     this.options = o.options;
+    // Fill missing options (always the case if random challenge)
+    (V.Options.select || []).concat(V.Options.input || []).forEach(opt => {
+      if (this.options[opt.variable] === undefined)
+        this.options[opt.variable] = opt.defaut;
+    });
     this.playerColor = o.color;
     this.afterPlay = o.afterPlay; //trigger some actions after playing a move
 
     this.initMouseEvents();
     const chessboard =
       document.getElementById(this.containerId).querySelector(".chessboard");
-    new ResizeObserver(this.rescale).observe(chessboard);
+    // TODO: calling with "this" seems required by Hex. Understand why...
+    new ResizeObserver(() => this.rescale(this)).observe(chessboard);
   }
 
   re_drawBoardElements() {
     let board = `
       <svg
         viewBox="0 0 80 80"
-        class="chessboard_SVG">
-      <g>`;
+        class="chessboard_SVG">`;
     for (let i=0; i < this.size.x; i++) {
       for (let j=0; j < this.size.y; j++) {
         const ii = (flipped ? this.size.x - 1 - i : i);
         if (this.enlightened && !this.enlightened[ii][jj])
           classes += " in-shadow";
         // NOTE: x / y reversed because coordinates system is reversed.
-        board += `<rect
-          class="${classes}"
-          id="${this.coordsToId({x: ii, y: jj})}"
-          width="10"
-          height="10"
-          x="${10*j}"
-          y="${10*i}" />`;
+        board += `
+          <rect
+            class="${classes}"
+            id="${this.coordsToId({x: ii, y: jj})}"
+            width="10"
+            height="10"
+            x="${10*j}"
+            y="${10*i}"
+          />`;
       }
     }
-    board += "</g></svg>";
+    board += "</svg>";
     return board;
   }
 
   }
 
   // After resize event: no need to destroy/recreate pieces
-  rescale() {
-    const container = document.getElementById(this.containerId);
+  rescale(self) {
+    const container = document.getElementById(self.containerId);
     if (!container)
       return; //useful at initial loading
     let chessboard = container.querySelector(".chessboard");
-    const r = chessboard.getBoundingClientRect();
-    const newRatio = r.width / r.height;
-    let newWidth = r.width,
-        newHeight = r.height;
-    if (newRatio > this.size.ratio) {
-      newWidth = r.height * this.size.ratio;
-      chessboard.style.width = newWidth + "px";
-    }
-    else if (newRatio < this.size.ratio) {
-      newHeight = r.width / this.size.ratio;
-      chessboard.style.height = newHeight + "px";
-    }
+    let r = chessboard.getBoundingClientRect();
+    let [newWidth, newHeight] = [r.width, r.height];
+    // Stay in window:
+    if (newWidth > window.innerWidth)
+      newWidth = window.innerWidth;
+    if (newHeight > window.innerHeight)
+      newHeight = window.innerHeight;
+    const newRatio = newWidth / newHeight;
+    if (newRatio > self.size.ratio)
+      newWidth = newHeight * self.size.ratio;
+    else if (newRatio < self.size.ratio)
+      newHeight = newWidth / self.size.ratio;
+    chessboard.style.width = newWidth + "px";
+    chessboard.style.height = newHeight + "px";
     const newX = (window.innerWidth - newWidth) / 2;
     chessboard.style.left = newX + "px";
     const newY = (window.innerHeight - newHeight) / 2;
     chessboard.style.top = newY + "px";
     const newR = {x: newX, y: newY, width: newWidth, height: newHeight};
-    const pieceWidth = this.getPieceWidth(newWidth);
+    const pieceWidth = self.getPieceWidth(newWidth);
     // NOTE: next "if" for variants which use squares filling
     // instead of "physical", moving pieces
     if (this.g_pieces) {
-      for (let i=0; i < this.size.x; i++) {
-        for (let j=0; j < this.size.y; j++) {
-          if (this.g_pieces[i][j]) {
+      for (let i=0; i < self.size.x; i++) {
+        for (let j=0; j < self.size.y; j++) {
+          if (self.g_pieces[i][j]) {
             // NOTE: could also use CSS transform "scale"
-            this.g_pieces[i][j].style.width = pieceWidth + "px";
-            this.g_pieces[i][j].style.height = pieceWidth + "px";
-            const [ip, jp] = this.getPixelPosition(i, j, newR);
+            self.g_pieces[i][j].style.width = pieceWidth + "px";
+            self.g_pieces[i][j].style.height = pieceWidth + "px";
+            const [ip, jp] = self.getPixelPosition(i, j, newR);
             // Translate coordinates to use chessboard as reference:
-            this.g_pieces[i][j].style.transform =
+            self.g_pieces[i][j].style.transform =
               `translate(${ip - newX}px,${jp - newY}px)`;
           }
         }
       }
     }
-    if (this.hasReserve)
-      this.rescaleReserve(newR);
+    if (self.hasReserve)
+      self.rescaleReserve(newR);
   }
 
   rescaleReserve(r) {
 
+++ /dev/null
-<?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<svg
-   xmlns:dc="http://purl.org/dc/elements/1.1/"
-   xmlns:cc="http://creativecommons.org/ns#"
-   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
-   xmlns:svg="http://www.w3.org/2000/svg"
-   xmlns="http://www.w3.org/2000/svg"
-   viewBox="0 0 860 1340"
-   height="1340"
-   width="860"
-   xml:space="preserve"
-   version="1.1"
-   id="svg2"><metadata
-     id="metadata8"><rdf:RDF><cc:Work
-         rdf:about=""><dc:format>image/svg+xml</dc:format><dc:type
-           rdf:resource="http://purl.org/dc/dcmitype/StillImage" /><dc:title></dc:title></cc:Work></rdf:RDF></metadata><defs
-     id="defs6" /><g
-     transform="matrix(1.25,0,0,-1.25,0,1340)"
-     id="g10"><path
-       id="path12"
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-// https://www.boardspace.net/hex/english/Rules%20-%20HexWiki.htm
+import ChessRules from "/base_rules.js";
+import PiPo from "/utils/PiPo.js";
+import Move from "/utils/Move.js";
+
 export default class HexRules extends ChessRules {
 
   static get Options() {
       input: [
         {
           label: "Board size",
+          variable: "bsize",
           type: "number",
-          defaut: 11,
-          variable: "bsize"
-        }
-      ],
-      check: [
+          defaut: 11
+        },
         {
           label: "Swap",
-          defaut: true,
-          variable: "swap"
+          variable: "swap",
+          type: "checkbox",
+          defaut: true
         }
       ]
     };
   }
 
+  get hasFlags() {
+    return false;
+  }
+  get hasEnpassant() {
+    return false;
+  }
   get hasReserve() {
     return false;
   }
 
   doClick(coords) {
     if (
-      this.board[coords.x][coords.y] != "" &&
-      (!this.swap || this.movesCount >= 2)
+      this.playerColor != this.turn ||
+      (
+        this.board[coords.x][coords.y] != "" &&
+        (!this.options["swap"] || this.movesCount >= 2)
+      )
     ) {
       return null;
     }
 
   genRandInitFen() {
     // NOTE: size.x == size.y (square boards)
-    const emptyCount = C.FenEmptySquares(this.size.x.repeat);
-    return (emptyCount + "/").repeat(this.size.x).slice(0, -1);
+    const emptyCount = C.FenEmptySquares(this.size.x);
+    return (emptyCount + "/").repeat(this.size.x).slice(0, -1) + " w 0";
   }
 
-  getPieceWidth(rwidth) {
-    return (rwidth / this.size.y); //TODO
-  }
-
-  // TODO
+  // TODO: re-enable rotation
   getSvgChessboard() {
+    // NOTE: with small margin seems nicer
+    let width = 173.2 * this.size.y + 173.2 * (this.size.y-1) / 2 + 30,
+        height = 50 + Math.floor(150 * this.size.x) + 30,
+        min_x = -86.6 - 15,
+        min_y = -100 - 15;
+//    if (this.size.rotate) {
+//      [width, height] = [height, width];
+//      [min_x, min_y] = [min_y, min_x];
+//    }
     let board = `
       <svg
-        width="2771.2px" height="1700px"
-        class="chessboard_SVG">
+        viewBox="${min_x} ${min_y} ${width} ${height}"
+        class="chessboard_SVG"`;
+//    if (this.size.rotate)
+//      board += ` transform="rotate(90 ${min_x} ${min_y})"`
+    board += `>
       <defs>
         <g id="hexa">
           <polygon
-            style="fill:none;stroke:#000000;stroke-width:1px"
+            style="stroke:#000000;stroke-width:1"
             points="0,-100.0 86.6,-50.0 86.6,50.0 0,100.0 -86.6,50.0 -86.6,-50.0"
           />
         </g>
       </defs>`;
+    board += "<g>";
     for (let i=0; i < this.size.x; i++) {
       for (let j=0; j < this.size.y; j++) {
-        let classes = this.getSquareColorClass(i, j);
-        board += `<rect
-          class="neutral-square"
-          id="${this.coordsToId([i, j])}"
-          width="10"
-          height="10"
-          x="${10*j}" ///////////// + resize ! ratio
-          y="${10*i}" />`;
+        board += `
+          <use
+            href="#hexa"
+            class="neutral-square"
+            id="${this.coordsToId({x: i, y: j})}"
+            x="${173.2*j + 86.6*i}"
+            y="${150*i}"
+          />`;
       }
     }
-    board += "</g></svg>";
+    board += `</g><g style="fill:none;stroke-width:10">`;
+    // Goals: up/down/left/right
+    board += `<polyline style="stroke:red" points="`
+    for (let i=0; i<=2*this.size.y; i++)
+      board += ((i-1)*86.6) + ',' + (i % 2 == 0 ? -50 : -100) + ' ';
+    board += `"/><polyline style="stroke:red" points="`;
+    for (let i=1; i<=2*this.size.y; i++) {
+      const jShift = 200 * Math.floor((this.size.y+1)/2) +
+                     100 * (Math.floor(this.size.y/2) - 1) +
+                     (i % 2 == 0 ? -50 : 0) +
+                     (this.size.y % 2 == 0 ? 50 : 0);
+      board += ((i+this.size.y-2)*86.6) + ',' + jShift + ' ';
+    }
+    board += `"/><polyline style="stroke:blue" points="`;
+    let sumY = -100;
+    for (let i=0; i<=2*this.size.x; i++) {
+      board += ((Math.floor(i/2)-1) * 86.6) + ',' +
+               (sumY += (i % 2 == 0 ? 50 : 100)) + ' ';
+    }
+    board += `"/><polyline style="stroke:blue" points="`;
+    sumY = -100;
+    for (let i=0; i<2*this.size.x; i++) {
+      board += (173.2*this.size.x + (Math.floor(i/2)-1) * 86.6) + ',' +
+               (sumY += (i % 2 == 0 ? 50 : 100)) + ' ';
+    }
+    board += `"/></g></svg>`;
     return board;
   }
 
   setupPieces() {
-    // TODO: just scan board and get IDs, and addClass "bg-white" or "bg-black"
-  }
-
-  // TODO (NOTE: no flip here, always same view)
-  getPixelPosition(i, j, r) {
-    if (i < 0 || j < 0)
-      return [0, 0]; //piece vanishes
-    let x, y;
-    const sqSize = r.width / this.size.y;
-    const flipped = (this.playerColor == 'b');
-    const x = (flipped ? this.size.y - 1 - j : j) * sqSize,
-          y = (flipped ? this.size.x - 1 - i : i) * sqSize;
-    return [r.x + x, r.y + y];
+    for (let i=0; i<this.size.x; i++) {
+      for (let j=0; j<this.size.y; j++) {
+        if (this.board[i][j] != "") {
+          const sqColor = (this.getColor(i, j) == 'w' ? "white" : "black");
+          const elt = document.getElementById(this.coordsToId({x: i, y: j}));
+          elt.classList.remove("neutral-square");
+          elt.classList.add("bg-" + sqColor);
+        }
+      }
+    }
   }
 
   initMouseEvents() {
   }
 
   get size() {
+    const baseRatio = 1.619191; // 2801.2 / 1730, "widescreen"
+    const rotate = window.innerWidth < window.innerHeight; //"vertical screen"
     return {
-      x: this.bsize,
-      y: this.bsize,
-      ratio: 1.630118
-    };
-  }
-
-  pieces() {
-    return {
-      'p': {
-        "class": "pawn",
-      }
+      x: this.options["bsize"],
+      y: this.options["bsize"],
+      ratio: rotate ? 1 / baseRatio : baseRatio,
+      rotate: rotate
     };
   }
 
   play(move) {
-    super.playOnBoard(move);
+    this.playOnBoard(move);
+    this.movesCount++;
+    this.turn = C.GetOppCol(this.turn);
   }
 
-  // TODO:
   getCurrentScore(move) {
     const oppCol = C.GetOppCol(this.turn);
-    // Search for connecting path of opp color: TODO
-    // ...
-    if (path found)
-      return (oppCol == "w" ? "1-0" : "0-1");
+    // Search for connecting path of opp color:
+    let explored = {}, component;
+    let min, max;
+    const getIndex = (x, y) => x + "." + y;
+    // Explore one connected component:
+    const neighborsSearch = ([x, y], index) => {
+      // Let's say "white" connects on x and "black" on y
+      const z = (oppCol == 'w' ? x : y);
+      if (z < min)
+        min = z;
+      if (z > max)
+        max = z;
+      explored[index] = true;
+      component[index] = true;
+      for (let [dx, dy] of super.pieces()['k'].moves[0].steps) {
+        const [nx, ny] = [x + dx, y + dy];
+        const nidx = getIndex(nx, ny);
+        if (
+          this.onBoard(nx, ny) &&
+          this.getColor(nx, ny) == oppCol &&
+          !component[nidx]
+        ) {
+          neighborsSearch([nx, ny], nidx);
+        }
+      }
+    };
+    // Explore all components:
+    for (let i=0; i<this.size.x; i++) {
+      for (let j=0; j<this.size.y; j++) {
+        const index = getIndex(i, j);
+        if (this.getColor(i, j) == oppCol && !explored[index]) {
+          component = {};
+          [min, max] = [this.size.x, 0];
+          neighborsSearch([i, j], index);
+          if (max - min == this.size.x - 1)
+            return (oppCol == "w" ? "1-0" : "0-1");
+        }
+      }
+    }
     return "*";
   }
 
   playVisual(move) {
     move.vanish.forEach(v => {
-// TODO: just get ID, and remClass "bg-white" or "bg-black" (in CSS: TODO)
+      let elt = document.getElementById(this.coordsToId({x: v.x, y: v.y}));
+      elt.classList.remove("bg-" + (v.c == 'w' ? "white" : "black"));
     });
     move.appear.forEach(a => {
-// TODO: just get ID, and addClass "bg-white" or "bg-black" (in CSS: TODO)
-//      this.g_pieces[a.x][a.y] = document.createElement("piece");
-//      this.g_pieces[a.x][a.y].classList.add(this.pieces()[a.p]["class"]);
-//      this.g_pieces[a.x][a.y].classList.add(a.c == "w" ? "white" : "black");
-//      this.g_pieces[a.x][a.y].style.width = pieceWidth + "px";
-//      this.g_pieces[a.x][a.y].style.height = pieceWidth + "px";
+      let elt = document.getElementById(this.coordsToId({x: a.x, y: a.y}));
+      elt.classList.add("bg-" + (a.c == 'w' ? "white" : "black"));
     });
   }