diff --git a/README.md b/README.md
index 08a8c8a..7b163e5 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,48 @@
-# android-omok-precourse
\ No newline at end of file
+# android-omok-precourse
+
+# 오목 게임
+
+이 프로젝트는 안드로이드를 위한 코틀린으로 구현된 간단한 오목(Omok) 게임이다. 
+이 게임은 두 명의 플레이어가 15 X 15 오목 판에 검은 돌과 흰 돌을 놓을 수 있게 하며, 전통적인 오목 규칙에 따라 진행된다. 추가로, 흑돌은 금수 규칙이 적용된다.
+
+
+## 주요 기능
+
+- **두 명의 플레이어**: 흑돌과 백돌.
+  
+- **기본 오목 규칙**: 가로, 세로 또는 대각선으로 다섯 개의 돌을 먼저 놓으면 승리
+- **흑돌 금수 규칙**:
+  - "삼삼" (Double Three): 두 개의 열린 삼을 만드는 돌 놓기 금지
+    
+  - "사사" (Double Four): 두 개의 열린 사를 만드는 돌 놓기 금지
+  - "장목" (Overline): 여섯 개 이상의 돌을 연속으로 놓는 것 금지
+- **백돌 자유 규칙**: 백돌은 아무 곳에나 놓을 수 있음
+- **승리 및 금수 위치 알림**: 승리 조건 충족 시 및 금수 위치에 돌을 놓으려 할 때 토스트 메시지로 알림
+
+
+
+## 파일 설명
+
+### MainActivity.kt
+
+`MainActivity`는 안드로이드 액티비티로서, 게임 보드를 설정하고 사용자 입력을 처리한다. 게임의 주요 로직은 `OmokGame` 클래스로 구현한다.
+
+
+### OmokGame.kt
+
+`OmokGame` 클래스는 게임의 상태를 관리하고, 금수 규칙과 승리 조건을 확인하는 로직을 포함한다.
+- 보드에 돌을 놓기
+- 플레이어 턴 전환
+- 가로, 세로, 대각선 승리 조건 확인
+- 삼삼, 사사, 장목과 같은 금수 규칙 적용
+
+### GameLogicTest.kt
+
+`GameLogicTest` 클래스는 JUnit 5와 AssertJ를 사용하여 `OmokGame`의 주요 기능을 테스트. 삼삼, 사사, 장목 금수 규칙과 승리 조건을 검증한다.
+
+- 가로 승리 조건
+- 세로 승리 조건
+- 대각선 승리 조건 (우하향, 우상향)
+- 흑돌 금수 규칙 (삼삼, 사사, 장목)
+
+
diff --git a/app/src/main/java/nextstep/omok/MainActivity.kt b/app/src/main/java/nextstep/omok/MainActivity.kt
index e6cc7b8..28d506c 100644
--- a/app/src/main/java/nextstep/omok/MainActivity.kt
+++ b/app/src/main/java/nextstep/omok/MainActivity.kt
@@ -4,20 +4,54 @@ import android.os.Bundle
 import android.widget.ImageView
 import android.widget.TableLayout
 import android.widget.TableRow
+import android.widget.Toast
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.view.children
 
 class MainActivity : AppCompatActivity() {
+
+    private val boardSize = 15
+    private lateinit var game: OmokGame
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
 
-        val board = findViewById<TableLayout>(R.id.board)
-        board
-            .children
+        game = OmokGame(boardSize)
+        setupBoard()
+    }
+
+    private fun setupBoard() {
+        val boardView = findViewById<TableLayout>(R.id.board)
+        boardView.children
             .filterIsInstance<TableRow>()
             .flatMap { it.children }
             .filterIsInstance<ImageView>()
-            .forEach { view -> view.setOnClickListener { view.setImageResource(R.drawable.black_stone) } }
+            .forEachIndexed { index, view ->
+                val row = index / boardSize
+                val col = index % boardSize
+                view.setOnClickListener { handleCellClick(row, col, view) }
+            }
+    }
+
+    private fun handleCellClick(row: Int, col: Int, view: ImageView) {
+        if (game.board[row][col] == 0) {
+            if (game.isForbidden(row, col)) {
+                Toast.makeText(this, "Forbidden move!", Toast.LENGTH_SHORT).show()
+                return
+            }
+            game.placeStone(row, col)
+            view.setImageResource(if (game.currentPlayer == 1) R.drawable.black_stone else R.drawable.white_stone)
+            if (game.checkWin(row, col, game.currentPlayer)) {
+                showWinner(game.currentPlayer)
+            } else {
+                game.switchPlayer()
+            }
+        }
+    }
+
+    private fun showWinner(player: Int) {
+        val winner = if (player == 1) "Black" else "White"
+        Toast.makeText(this, "$winner wins!", Toast.LENGTH_SHORT).show()
     }
 }
diff --git a/app/src/main/java/nextstep/omok/OmokGame.kt b/app/src/main/java/nextstep/omok/OmokGame.kt
new file mode 100644
index 0000000..7ccc968
--- /dev/null
+++ b/app/src/main/java/nextstep/omok/OmokGame.kt
@@ -0,0 +1,123 @@
+package nextstep.omok
+
+class OmokGame(private val boardSize: Int) {
+
+    val board = Array(boardSize) { Array(boardSize) { 0 } }
+    var currentPlayer = 1 // 1 for black, 2 for white
+
+    fun placeStone(row: Int, col: Int): Boolean {
+        if (board[row][col] == 0) {
+            board[row][col] = currentPlayer
+            return true
+        }
+        return false
+    }
+
+    fun switchPlayer() {
+        currentPlayer = if (currentPlayer == 1) 2 else 1
+    }
+
+    fun checkWin(row: Int, col: Int, player: Int): Boolean {
+        return checkDirection(row, col, player, 0, 1) >= 5 || // Horizontal
+                checkDirection(row, col, player, 1, 0) >= 5 || // Vertical
+                checkDirection(row, col, player, 1, 1) >= 5 || // Diagonal down-right
+                checkDirection(row, col, player, 1, -1) >= 5   // Diagonal up-right
+    }
+
+    fun isForbidden(row: Int, col: Int): Boolean {
+        if (currentPlayer == 1) {
+            return isDoubleThree(row, col) || isDoubleFour(row, col) || isSixInARow(row, col)
+        }
+        return false
+    }
+
+    private fun checkDirection(row: Int, col: Int, player: Int, dRow: Int, dCol: Int): Int {
+        var count = 1
+        count += countStones(row, col, player, dRow, dCol)
+        count += countStones(row, col, player, -dRow, -dCol)
+        return count
+    }
+
+    private fun countStones(row: Int, col: Int, player: Int, dRow: Int, dCol: Int): Int {
+        var count = 0
+        var r = row + dRow
+        var c = col + dCol
+        while (r in 0 until boardSize && c in 0 until boardSize && board[r][c] == player) {
+            count++
+            r += dRow
+            c += dCol
+        }
+        return count
+    }
+
+    fun isDoubleThree(row: Int, col: Int): Boolean {
+        return countOpenThrees(row, col, 1, 0) + countOpenThrees(row, col, 0, 1) +
+                countOpenThrees(row, col, 1, 1) + countOpenThrees(row, col, 1, -1) > 1
+    }
+
+    private fun countOpenThrees(row: Int, col: Int, dRow: Int, dCol: Int): Int {
+        var count = 0
+        if (isOpenThree(row, col, dRow, dCol)) count++
+        if (isOpenThree(row, col, -dRow, -dCol)) count++
+        return count
+    }
+
+    private fun isOpenThree(row: Int, col: Int, dRow: Int, dCol: Int): Boolean {
+        val sequence = mutableListOf<Int>()
+        for (i in -4..4) {
+            val r = row + i * dRow
+            val c = col + i * dCol
+            if (r in 0 until boardSize && c in 0 until boardSize) {
+                sequence.add(board[r][c])
+            } else {
+                sequence.add(-1)
+            }
+        }
+        val pattern = listOf(0, 1, 1, 1, 0)
+        for (i in 0..sequence.size - pattern.size) {
+            if (sequence.subList(i, i + pattern.size) == pattern) {
+                return true
+            }
+        }
+        return false
+    }
+
+    fun isDoubleFour(row: Int, col: Int): Boolean {
+        return countOpenFours(row, col, 1, 0) + countOpenFours(row, col, 0, 1) +
+                countOpenFours(row, col, 1, 1) + countOpenFours(row, col, 1, -1) > 1
+    }
+
+    private fun countOpenFours(row: Int, col: Int, dRow: Int, dCol: Int): Int {
+        var count = 0
+        if (isOpenFour(row, col, dRow, dCol)) count++
+        if (isOpenFour(row, col, -dRow, -dCol)) count++
+        return count
+    }
+
+    private fun isOpenFour(row: Int, col: Int, dRow: Int, dCol: Int): Boolean {
+        val sequence = mutableListOf<Int>()
+        for (i in -4..4) {
+            val r = row + i * dRow
+            val c = col + i * dCol
+            if (r in 0 until boardSize && c in 0 until boardSize) {
+                sequence.add(board[r][c])
+            } else {
+                sequence.add(-1)
+            }
+        }
+        val pattern = listOf(0, 1, 1, 1, 1, 0)
+        for (i in 0..sequence.size - pattern.size) {
+            if (sequence.subList(i, i + pattern.size) == pattern) {
+                return true
+            }
+        }
+        return false
+    }
+
+    fun isSixInARow(row: Int, col: Int): Boolean {
+        return checkDirection(row, col, currentPlayer, 0, 1) > 5 ||
+                checkDirection(row, col, currentPlayer, 1, 0) > 5 ||
+                checkDirection(row, col, currentPlayer, 1, 1) > 5 ||
+                checkDirection(row, col, currentPlayer, 1, -1) > 5
+    }
+}
diff --git a/app/src/test/java/nextstep/omok/GameLogicTest.kt b/app/src/test/java/nextstep/omok/GameLogicTest.kt
new file mode 100644
index 0000000..f64d5bc
--- /dev/null
+++ b/app/src/test/java/nextstep/omok/GameLogicTest.kt
@@ -0,0 +1,93 @@
+package nextstep.omok
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+
+class GameLogicTest {
+
+    private val boardSize = 15
+    private lateinit var game: OmokGame
+
+    @BeforeEach
+    fun setUp() {
+        game = OmokGame(boardSize)
+    }
+
+    @Test
+    fun `horizontal win check`() {
+        for (i in 0 until 5) {
+            game.board[0][i] = 1
+        }
+        val result = game.checkWin(0, 2, 1)
+        assertThat(result).isTrue()
+    }
+
+    @Test
+    fun `vertical win check`() {
+        for (i in 0 until 5) {
+            game.board[i][0] = 1
+        }
+        val result = game.checkWin(2, 0, 1)
+        assertThat(result).isTrue()
+    }
+
+    @Test
+    fun `diagonal down-right win check`() {
+        for (i in 0 until 5) {
+            game.board[i][i] = 1
+        }
+        val result = game.checkWin(2, 2, 1)
+        assertThat(result).isTrue()
+    }
+
+    @Test
+    fun `diagonal up-right win check`() {
+        for (i in 0 until 5) {
+            game.board[4 - i][i] = 1
+        }
+        val result = game.checkWin(2, 2, 1)
+        assertThat(result).isTrue()
+    }
+
+    @Test
+    fun `double three forbidden move`() {
+        // Set up a double three situation
+        game.board[1][2] = 1
+        game.board[1][3] = 1
+        game.board[1][5] = 1
+        game.board[1][6] = 1
+        game.board[2][3] = 1
+        game.board[3][3] = 1
+        game.board[4][3] = 1
+
+        val result = game.isDoubleThree(1, 4)
+        assertThat(result).isTrue()
+    }
+
+    @Test
+    fun `double four forbidden move`() {
+        // Set up a double four situation
+        game.board[1][2] = 1
+        game.board[1][3] = 1
+        game.board[1][4] = 1
+        game.board[1][6] = 1
+        game.board[1][7] = 1
+        game.board[1][8] = 1
+        game.board[0][5] = 1
+        game.board[2][5] = 1
+
+        val result = game.isDoubleFour(1, 5)
+        assertThat(result).isTrue()
+    }
+
+    @Test
+    fun `six in a row forbidden move`() {
+        // Set up a six in a row situation
+        for (i in 0 until 6) {
+            game.board[0][i] = 1
+        }
+        val result = game.isSixInARow(0, 2)
+        assertThat(result).isTrue()
+    }
+}