diff --git a/src/app/TetrisApp.cpp b/src/app/TetrisApp.cpp
index 0b0db60..db0b29e 100644
--- a/src/app/TetrisApp.cpp
+++ b/src/app/TetrisApp.cpp
@@ -685,6 +685,13 @@ void TetrisApp::Impl::runLoop()
                 challengeClearFxOrder.push_back(idx);
             }
         }
+        // Seed FX RNG deterministically from the game's challenge seed so animations
+        // are reproducible per-run and per-level. Fall back to a random seed if game absent.
+        if (game) {
+            challengeClearFxRng.seed(game->getChallengeSeedBase() + static_cast<uint32_t>(nextLevel));
+        } else {
+            challengeClearFxRng.seed(std::random_device{}());
+        }
         std::shuffle(challengeClearFxOrder.begin(), challengeClearFxOrder.end(), challengeClearFxRng);
 
         challengeClearFxElapsedMs = 0.0;
diff --git a/src/gameplay/core/Game.cpp b/src/gameplay/core/Game.cpp
index aab6c90..8a560a0 100644
--- a/src/gameplay/core/Game.cpp
+++ b/src/gameplay/core/Game.cpp
@@ -278,7 +278,7 @@ void Game::placeAsteroidsForLevel(int level) {
         }
         AsteroidType type = chooseAsteroidTypeForLevel(level);
         AsteroidCell cell = makeAsteroidForType(type);
-        board[idx] = ASTEROID_BASE + static_cast<int>(type);
+        board[idx] = asteroidBoardValue(type);
         asteroidGrid[idx] = cell;
         ++asteroidsRemainingCount;
         ++asteroidsTotalThisLevel;
@@ -289,6 +289,22 @@ void Game::placeAsteroidsForLevel(int level) {
     }
 }
 
+// Helper implementations for asteroid board encoding
+bool Game::isAsteroidValue(int boardValue) {
+    return boardValue >= ASTEROID_BASE;
+}
+
+AsteroidType Game::asteroidTypeFromValue(int boardValue) {
+    int idx = boardValue - ASTEROID_BASE;
+    if (idx < 0) return AsteroidType::Normal;
+    if (idx > static_cast<int>(AsteroidType::Core)) idx = static_cast<int>(AsteroidType::Core);
+    return static_cast<AsteroidType>(idx);
+}
+
+int Game::asteroidBoardValue(AsteroidType t) {
+    return ASTEROID_BASE + static_cast<int>(t);
+}
+
 double Game::elapsed() const {
     if (!_startTime) return 0.0;
     
@@ -519,11 +535,8 @@ int Game::checkLines() {
         for (int y : completedLines) {
             for (int x = 0; x < COLS; ++x) {
                 int idx = y * COLS + x;
-                if (board[idx] >= ASTEROID_BASE) {
-                    int typeIdx = board[idx] - ASTEROID_BASE;
-                    if (typeIdx >= 0 && typeIdx <= static_cast<int>(AsteroidType::Core)) {
-                        foundType = static_cast<AsteroidType>(typeIdx);
-                    }
+                if (isAsteroidValue(board[idx])) {
+                    foundType = asteroidTypeFromValue(board[idx]);
                 } else if (idx >= 0 && idx < static_cast<int>(asteroidGrid.size()) && asteroidGrid[idx].has_value()) {
                     foundType = asteroidGrid[idx]->type;
                 }
@@ -643,7 +656,7 @@ void Game::handleAsteroidsOnClearedRows(const std::vector<int>& clearedRows,
                     continue; // off the board after collapse
                 }
                 int destIdx = destY * COLS + x;
-                outBoard[destIdx] = ASTEROID_BASE + static_cast<int>(cell.type);
+                outBoard[destIdx] = asteroidBoardValue(cell.type);
                 outAsteroids[destIdx] = cell;
             } else {
                 int destY = y + clearedBelow[y];
diff --git a/src/gameplay/core/Game.h b/src/gameplay/core/Game.h
index 920ff97..4899f06 100644
--- a/src/gameplay/core/Game.h
+++ b/src/gameplay/core/Game.h
@@ -185,6 +185,15 @@ private:
 
     // Recent asteroid explosion positions (grid coords) for renderer FX
     std::vector<SDL_Point> recentAsteroidExplosions;
+    
+    // Expose the internal challenge seed base for deterministic FX/RNG coordination
+public:
+    uint32_t getChallengeSeedBase() const { return challengeSeedBase; }
+
+    // Helpers for board encoding of asteroids
+    static bool isAsteroidValue(int boardValue);
+    static AsteroidType asteroidTypeFromValue(int boardValue);
+    static int asteroidBoardValue(AsteroidType t);
 
     // Internal helpers ----------------------------------------------------
     void refillBag();