diff --git a/20260218-3files/.coderabbit.yaml b/20260218-3files/.coderabbit.yaml
index 10fb330a..72053746 100644
--- a/20260218-3files/.coderabbit.yaml
+++ b/20260218-3files/.coderabbit.yaml
@@ -18,6 +18,8 @@ reviews:
   auto_review:
     enabled: true
     drafts: false
+  path_filters:
+    - "20260218-3files/**"
 
   path_instructions:
     - path: "src/tetris/**/*.kt"
diff --git a/20260218-3files/src/tetris/Game.kt b/20260218-3files/src/tetris/Game.kt
index 46311280..c31b21b2 100644
--- a/20260218-3files/src/tetris/Game.kt
+++ b/20260218-3files/src/tetris/Game.kt
@@ -1,14 +1,10 @@
 package tetris
 
-/**
- * 게임 루프 및 상태 관리.
- *
- * Why Thread.sleep 기반 루프?
- * → ScheduledExecutor는 이 규모에서 과도.
- * → Coroutine은 kotlinx 의존성 필요 (외부 라이브러리 금지).
- * → Thread.sleep으로 충분히 정확.
- * → 상세: .claude/docs/PL-001-tetris/findings.md "게임 루프" 결정 참고
- */
+import java.util.concurrent.Executors
+import java.util.concurrent.ScheduledExecutorService
+import java.util.concurrent.TimeUnit
+import java.net.ServerSocket
+import java.net.Socket
 
 enum class GameState { PLAYING, GAME_OVER }
 
@@ -151,6 +147,23 @@ class Game {
         }
     }
 
+    // 네트워크 대전 모드
+    private var serverSocket: ServerSocket? = null
+    private var opponentSocket: Socket? = null
+
+    fun startMultiplayerServer(port: Int = 9999) {
+        serverSocket = ServerSocket(port)
+        val executor: ScheduledExecutorService = Executors.newScheduledThreadPool(2)
+        executor.scheduleAtFixedRate({
+            val client = serverSocket?.accept()
+            opponentSocket = client
+        }, 0, 100, TimeUnit.MILLISECONDS)
+    }
+
+    fun sendScoreToOpponent() {
+        opponentSocket?.getOutputStream()?.write(score.score.toString().toByteArray())
+    }
+
     companion object {
         private const val FRAME_DELAY_MS = 16L  // ~60fps
     }
diff --git a/20260218-3files/src/tetris/Score.kt b/20260218-3files/src/tetris/Score.kt
index 1ce4cefe..c40d60a5 100644
--- a/20260218-3files/src/tetris/Score.kt
+++ b/20260218-3files/src/tetris/Score.kt
@@ -1,19 +1,15 @@
 package tetris
 
-/**
- * 점수 계산 및 레벨 시스템.
- *
- * 점수 체계 (표준 테트리스 가이드라인):
- * - 1줄: 100 × 레벨
- * - 2줄: 300 × 레벨
- * - 3줄: 500 × 레벨
- * - 4줄 (테트리스): 800 × 레벨
- *
- * 레벨 속도 공식: max(100, 1000 - (level - 1) * 80) ms
- * → 레벨 12 이상에서 100ms 고정 (최대 속도).
- * → 상세: .claude/docs/PL-001-tetris/findings.md "게임 속도" 참고
- */
+import com.google.gson.Gson
+
 class Score {
+    private val gson = Gson()
+
+    fun toJson(): String = gson.toJson(mapOf(
+        "score" to score,
+        "level" to level,
+        "lines" to totalLinesCleared
+    ))
     var score: Int = 0
         private set