diff --git a/index.js b/index.js
index 7553909..fbf3d52 100644
--- a/index.js
+++ b/index.js
@@ -2,23 +2,47 @@ const CROSS = 'X';
 const ZERO = 'O';
 const EMPTY = ' ';
 
+let field;
+let maxTurns;
+let turn;
+let winCombination;
+let isGameOver;
+let winner;
+let expansionEnabled;
+
+const winTypes = {
+    horizontal: 'horiz',
+    vertical: 'vert',
+    diagonalLeft: 'diagL',
+    diagonalRight: 'diagR'
+}
+
 const container = document.getElementById('fieldWrapper');
 
 startGame();
 addResetListener();
 
-function startGame () {
-    renderGrid(3);
+function startGame() {
+    field = [];
+    turn = 0;
+    winCombination = [];
+    isGameOver = false;
+    winner = "";
+    let dimension = prompt("Задайте размер поля:", 3);
+    for (let y = 0; y < dimension; y++)
+        field[y] = [];
+    expansionEnabled = confirm("Включить автоматическое расширение поля?");
+    renderGrid(dimension);
 }
 
-function renderGrid (dimension) {
+function renderGrid(dimension) {
     container.innerHTML = '';
-
+    maxTurns = dimension ** 2;
     for (let i = 0; i < dimension; i++) {
         const row = document.createElement('tr');
         for (let j = 0; j < dimension; j++) {
             const cell = document.createElement('td');
-            cell.textContent = EMPTY;
+            cell.textContent = field[i][j] === undefined ? EMPTY : field[i][j];
             cell.addEventListener('click', () => cellClickHandler(i, j));
             row.appendChild(cell);
         }
@@ -26,41 +50,194 @@ function renderGrid (dimension) {
     }
 }
 
-function cellClickHandler (row, col) {
-    // Пиши код тут
+function cellClickHandler(row, col) {
+    if (isGameOver) return;
     console.log(`Clicked on cell: ${row}, ${col}`);
+    if (field[row][col] !== undefined)
+        return;
+    field[row][col] = CROSS;
+    processClick(field[row][col], row, col);
+    if (!isGameOver) botClick();
+}
+
+function botClick() {
+    if (isGameOver) return;
+    let freeCellCount = field.length ** 2 - turn;
+    let randomFreeCell = Math.floor(Math.random() * freeCellCount);
+    let row, col;
+    let symbol = ZERO;
+    [row, col] = getCellCoords(randomFreeCell, symbol);
+    console.log(`Bot clicked on cell: ${row}, ${col}`);
+    field[row][col] = symbol;
+    processClick(field[row][col], row, col);
+}
+
+function getCellCoords(randomFreeCell, symbol) {
+    let counter = 0;
+    let winRow, winCol, randRow, randCol;
+    cellSearch: for (let y = 0; y < field.length; y++)
+        for (let x = 0; x < field.length; x++) {
+            if (field[y][x] === undefined) {
+                if (counter === randomFreeCell)
+                    [randRow, randCol] = [y, x];
+                field[y][x] = symbol;
+                winner = checkWinner(symbol, y, x);
+                if (winner !== symbol) field[y][x] = undefined;
+                else {
+                    [winRow, winCol] = [y, x];
+                    break cellSearch;
+                }
+                counter++;
+            }
+        }
+    if (winner !== symbol)
+        return [randRow, randCol];
+    return [winRow, winCol];
+}
+
+function processClick(symbol, row, col) {
+    renderSymbolInCell(symbol, row, col);
+    winner = checkWinner(symbol, row, col);
+    turn++;
+    if (expansionEnabled && turn * 2 >= field.length ** 2) {
+        field = expandField();
+        renderGrid(field.length);
+    }
+
+    if (turn === maxTurns && !winner) isGameOver = true;
+    else if (!winner) return;
+    //console.log(isGameOver);
+    colorWinningLine();
+    announceWinner();
+}
+
+function checkWinner(symbol, row, col) {
+    winCombination = checkForWinCombination(symbol, row, col);
+    //console.log(winCombination);
+    if (winCombination.length === field.length) {
+        isGameOver = true;
+        return symbol;
+    }
+    return "";
+}
 
+function checkForWinCombination(symbol, row, col) {
+    if ((col === 0 || field[row][col - 1] === symbol) &&
+        (col === field.length - 1 || field[row][col + 1] === symbol))
+        return getWinCombination(winTypes.horizontal, symbol, row, col);
 
-    /* Пользоваться методом для размещения символа в клетке так:
-        renderSymbolInCell(ZERO, row, col);
-     */
+    if ((row === 0 || field[row - 1][col] === symbol) &&
+        (row === field.length - 1 || field[row + 1][col] === symbol))
+        return getWinCombination(winTypes.vertical, symbol, row, col);
+
+    if (row === col &&
+        (row === 0 || field[row - 1][col - 1] === symbol) &&
+        (row === field.length - 1 || field[row + 1][col + 1] === symbol))
+        return getWinCombination(winTypes.diagonalLeft, symbol, row, col);
+
+    if (field.length - 1 - row === col &&
+        (row === 0 || field[row - 1][col + 1] === symbol) &&
+        (col === 0 || field[row + 1][col - 1] === symbol))
+        return getWinCombination(winTypes.diagonalRight, symbol, row, col);
+    return [];
+}
+
+function getWinCombination(winType, symbol, row, col) {
+    let combination = []
+    combAssembly: for (let i = 0; i < field.length; i++) {
+        switch (winType) {
+            case winTypes.vertical:
+                if (field[i][col] !== symbol)
+                    break combAssembly;
+                combination.push([i, col]);
+                break;
+            case winTypes.horizontal:
+                if (field[row][i] !== symbol)
+                    break combAssembly;
+                combination.push([row, i]);
+                break;
+            case winTypes.diagonalLeft:
+                if (field[i][i] !== symbol)
+                    break combAssembly;
+                combination.push([i, i]);
+                break;
+            case winTypes.diagonalRight:
+                if (field[field.length - 1 - i][i] !== symbol)
+                    break combAssembly;
+                combination.push([field.length - 1 - i, i])
+                break;
+        }
+    }
+    if (combination.length === field.length)
+        return combination;
+    return [];
+}
+
+function expandField() {
+    let newSize = field.length + 2;
+    maxTurns = newSize ** 2;
+    let newField = [];
+    for (let y = 0; y < newSize; y++)
+        newField[y] = [];
+
+    for (let y = 0; y < field.length; y++)
+        for (let x = 0; x < field.length; x++)
+            newField[y + 1][x + 1] = field[y][x];
+
+    console.log("Field expanded!");
+    return newField;
+}
+
+function announceWinner() {
+    if (!isGameOver) return;
+    switch (winner) {
+        case CROSS:
+            alert('Победили крестики!');
+            break;
+        case ZERO:
+            alert('Победили нолики!');
+            break;
+        default:
+            alert('Победила дружба!');
+            break;
+    }
+}
+
+function colorWinningLine() {
+    for (let i = 0; i < winCombination.length; i++) {
+        let row = winCombination[i][0];
+        let col = winCombination[i][1];
+        const targetCell = findCell(row, col);
+        targetCell.style.backgroundColor = "red";
+    }
 }
 
-function renderSymbolInCell (symbol, row, col, color = '#333') {
+function renderSymbolInCell(symbol, row, col, color = '#333') {
     const targetCell = findCell(row, col);
 
     targetCell.textContent = symbol;
     targetCell.style.color = color;
 }
 
-function findCell (row, col) {
+function findCell(row, col) {
     const targetRow = container.querySelectorAll('tr')[row];
     return targetRow.querySelectorAll('td')[col];
 }
 
-function addResetListener () {
+function addResetListener() {
     const resetButton = document.getElementById('reset');
     resetButton.addEventListener('click', resetClickHandler);
 }
 
-function resetClickHandler () {
+function resetClickHandler() {
     console.log('reset!');
+    startGame();
 }
 
 
 /* Test Function */
 /* Победа первого игрока */
-function testWin () {
+function testWin() {
     clickOnCell(0, 2);
     clickOnCell(0, 0);
     clickOnCell(2, 0);
@@ -71,7 +248,7 @@ function testWin () {
 }
 
 /* Ничья */
-function testDraw () {
+function testDraw() {
     clickOnCell(2, 0);
     clickOnCell(1, 0);
     clickOnCell(1, 1);
@@ -84,6 +261,6 @@ function testDraw () {
     clickOnCell(2, 2);
 }
 
-function clickOnCell (row, col) {
+function clickOnCell(row, col) {
     findCell(row, col).click();
 }