diff --git a/headers/config.h b/headers/config.h
index ce664a1..884a3c7 100644
--- a/headers/config.h
+++ b/headers/config.h
@@ -19,6 +19,8 @@ public:
 	unsigned torpedo_length; // auto defined from width
 	unsigned player_width;
 
+	unsigned alien_speed;
+
 	bool loadConfig();
 };
 
diff --git a/headers/game.h b/headers/game.h
index 1ad40ec..f6bf4aa 100644
--- a/headers/game.h
+++ b/headers/game.h
@@ -13,9 +13,11 @@ class Game {
 private:
     PixelManager pm;
 	Config conf;
-	unsigned baseX;
-	unsigned baseY;
+
+	position basePos;
 	aliensGrid grid;
+	bool direction = true;
+
     vector<missile> missiles;
     vector<torpedo> torpedos;
 	unsigned playerX;
@@ -31,6 +33,7 @@ private:
 	void moveTorpedos();
 	bool checkMissilesAndPlayer();
 	bool checkTorpedosAndInvaders();
+	bool invadersTouchFloor();
 public:
 	// in case someone wants to mess with the code, here's a minimal API, costs nothing to us
     Game();
diff --git a/src/game_basics.cpp b/src/game_basics.cpp
index e9f7c8c..dbca7ff 100644
--- a/src/game_basics.cpp
+++ b/src/game_basics.cpp
@@ -33,6 +33,16 @@ void Game::deathMenuHandler(){
 			// potential options...
 	}
 }
+
+bool Game::invadersTouchFloor(){
+	for(aliensLine& line : grid){
+		if(basePos.getY()+line.size()*conf.alien_size>=pm.getScreenHeight()){
+			return true;
+		}
+	}
+	return false;
+}
+
 /**
  * Plays the game, and returns once the game is finished
  *
@@ -46,7 +56,7 @@ unsigned Game::playGame(){ // returns when game is finished
 	// GAMELOOP
 	while(true){
 		managePlayer();
-		if(manageInvaders())return INVADERS_WINS;
+		if(manageInvaders() && invadersTouchFloor())return INVADERS_WINS;
 		unsigned res = manageAllCollisions(); // also advances missiles + torpedos
 		if(res!=0)return res;
 		display();
@@ -60,8 +70,8 @@ void Game::display() {
 	for (unsigned i = 0; i < this->grid.size(); ++i){
 		for (unsigned j = 0; j < this->grid[0].size(); ++j){
 			pm.dessinerInvader1(nsGraphics::Vec2D(
-				baseX+j*conf.alien_size+j*conf.distance,
-				baseY+i*conf.alien_size+i*conf.distance
+				basePos.getX()+j*conf.alien_size+j*conf.distance,
+				basePos.getY()+i*conf.alien_size+i*conf.distance
 			));
 		}
 	}
diff --git a/src/game_managers.cpp b/src/game_managers.cpp
index 84d7f5a..83f3b1a 100644
--- a/src/game_managers.cpp
+++ b/src/game_managers.cpp
@@ -11,9 +11,32 @@ void Game::managePlayer(){
 
 /** Makes the invaders play once, and check lower bounds
  *
- * @return true if the invaders crossed the first line of the grid, else false
+ * @return true if the invaders went down from one line (and we should check boundaries), else false
 */
 bool Game::manageInvaders(){
+	if(direction){ // go to the right
+		int end = basePos.getX(); // start position
+		end+= grid.size()*conf.alien_size; // add the aliens
+		end+= (grid.size()-1)*conf.distance; // add the distance between aliens
+
+		// you got the end !
+
+		if(end+conf.alien_speed<pm.getScreenWidth()){
+			basePos.setX(basePos.getX()+conf.alien_speed);
+		}else{
+			basePos.setY(basePos.getY()-conf.alien_size);
+			direction = !direction;
+			return true;
+		}
+	}else{
+		if(basePos.getX()-conf.alien_size>=0){
+			basePos.setX(basePos.getX()-conf.alien_speed);
+		}else{
+			basePos.setY(basePos.getY()-conf.alien_size);
+			direction = !direction;
+			return true;
+		}
+	}
 	return false;
 
 }
diff --git a/src/pixelManager.cpp b/src/pixelManager.cpp
index 73906ca..86df221 100644
--- a/src/pixelManager.cpp
+++ b/src/pixelManager.cpp
@@ -45,4 +45,8 @@ unsigned PixelManager::showDeathMenu() {
 
 unsigned PixelManager::getScreenHeight() {
 	return 0;
+}
+
+unsigned PixelManager::getScreenWidth() {
+	return 0;
 }
\ No newline at end of file