diff --git a/src/main/java/lab/BulletAnimated.java b/src/main/java/lab/BulletAnimated.java
index 27eae34736d28868aab2184cba9125bf188d4be8..bfe0a20c81daf4414b2022c10de4cf95efa40b9b 100644
--- a/src/main/java/lab/BulletAnimated.java
+++ b/src/main/java/lab/BulletAnimated.java
@@ -5,7 +5,7 @@ import javafx.geometry.Rectangle2D;
 import javafx.scene.canvas.GraphicsContext;
 import javafx.scene.image.Image;
 
-public class BulletAnimated {
+public class BulletAnimated  implements DrawableSimulable, Collisionable{
 
 	private Point2D position;
 	private Point2D start;
@@ -85,6 +85,10 @@ public class BulletAnimated {
 		return getBoundingBox().intersects(dragon.getBoundingBox());
 	}
 	
+	public void hitBy(Collisionable other) {
+		reload();
+	}
+	
 	public void reload() {
 		position = start;
 		speed = initialSpeed;
diff --git a/src/main/java/lab/Cannon.java b/src/main/java/lab/Cannon.java
index 92c54310524127224b89db59c3b840b7709df328..eb3f7894ff90af890ddf6ff1fda29560ed9e6ae1 100644
--- a/src/main/java/lab/Cannon.java
+++ b/src/main/java/lab/Cannon.java
@@ -5,7 +5,7 @@ import javafx.scene.canvas.GraphicsContext;
 import javafx.scene.paint.Color;
 import javafx.scene.transform.Affine;
 
-public class Cannon {
+public class Cannon implements DrawableSimulable {
 
 	private int direction=-1;
 	private double angle = 0;
diff --git a/src/main/java/lab/Collisionable.java b/src/main/java/lab/Collisionable.java
new file mode 100644
index 0000000000000000000000000000000000000000..3cf3eb47a6f35f44afb648346fe987018a6bd37c
--- /dev/null
+++ b/src/main/java/lab/Collisionable.java
@@ -0,0 +1,13 @@
+package lab;
+
+import javafx.geometry.Rectangle2D;
+
+public interface Collisionable {
+	Rectangle2D getBoundingBox();
+	
+	default boolean intersects(Collisionable other) {
+		return getBoundingBox().intersects(other.getBoundingBox());
+	}
+	
+	void hitBy(Collisionable other);
+}
diff --git a/src/main/java/lab/Dragon.java b/src/main/java/lab/Dragon.java
index 216628afbd03d95d4896abc8b5175efcb25709c8..987de596cda5ceedf27c903d421432003e5acfea 100644
--- a/src/main/java/lab/Dragon.java
+++ b/src/main/java/lab/Dragon.java
@@ -4,7 +4,7 @@ import javafx.geometry.Point2D;
 import javafx.geometry.Rectangle2D;
 import javafx.scene.canvas.GraphicsContext;
 
-public class Dragon {
+public class Dragon implements DrawableSimulable, Collisionable{
 	
 	private Point2D position;
 	
@@ -21,13 +21,13 @@ public class Dragon {
 		this.speed = speed;
 	}
 
-	
+	@Override
 	public void draw(GraphicsContext gc) {
 		Point2D canvasPosition = world.getCanvasPoint(position);
 		gc.drawImage(Constants.DRAGON_IMAGE, canvasPosition.getX(), canvasPosition.getY(), size, size);
 	}
 
-
+	@Override
 	public void simulate(double timeDelta) {
 		double timeDeltaS = timeDelta;
 		double newX = (position.getX() + speed.getX() * timeDeltaS + world.getWidth()) % world.getWidth(); 
@@ -45,6 +45,14 @@ public class Dragon {
 		speed = speed.multiply(-1.);
 	}
 
+
+	@Override
+	public void hitBy(Collisionable other) {
+		if (!(other instanceof Dragon)) {
+			hit();
+		}
+	}
+
 	
 	
 	
diff --git a/src/main/java/lab/DrawableSimulable.java b/src/main/java/lab/DrawableSimulable.java
new file mode 100644
index 0000000000000000000000000000000000000000..2942fa2caa6051f280bde318b162db8bae105598
--- /dev/null
+++ b/src/main/java/lab/DrawableSimulable.java
@@ -0,0 +1,11 @@
+package lab;
+
+import javafx.scene.canvas.GraphicsContext;
+
+public interface DrawableSimulable {
+	
+	void draw(GraphicsContext gc);
+	
+	void simulate(double deltaT);
+	
+}
diff --git a/src/main/java/lab/World.java b/src/main/java/lab/World.java
index ce631f92042437d374ab6c311c2778450a88858c..592805624cfb873aadbf736d06b05814a449090b 100644
--- a/src/main/java/lab/World.java
+++ b/src/main/java/lab/World.java
@@ -7,17 +7,16 @@ import javafx.scene.canvas.GraphicsContext;
 public class World {
 	private double width;
 	private double height;
-	private BulletAnimated bulletAnimatted;
-	private Cannon cannon;
-	private Dragon[] dragons;
-
+	private DrawableSimulable []entities; 
+	
 	public World(double width, double height) {
 		super();
 		this.width = width;
 		this.height = height;
-		cannon = new Cannon(this, new Point2D(50, 50), new Point2D(100, 20));
-		bulletAnimatted = new BulletAnimated(this, cannon, new Point2D(30, 60), new Point2D(0, 0), 40);
-		dragons = new Dragon[] { new Dragon(this, new Point2D(50, 200), new Point2D(100, 5)),
+		Cannon cannon = new Cannon(this, new Point2D(50, 50), new Point2D(100, 20));
+		entities = new DrawableSimulable[] { cannon,
+				new BulletAnimated(this, cannon, new Point2D(30, 60), new Point2D(0, 0), 40),
+				new Dragon(this, new Point2D(50, 200), new Point2D(100, 5)),
 				new Dragon(this, new Point2D(50, 230), new Point2D(60, 5)),
 				new Dragon(this, new Point2D(50, 270), new Point2D(-50, 20)) };
 	}
@@ -29,23 +28,37 @@ public class World {
 	public void draw(Canvas canvas) {
 		GraphicsContext gc = canvas.getGraphicsContext2D();
 		gc.clearRect(0, 0, canvas.getWidth(), canvas.getHeight());
-		cannon.draw(gc);
-		bulletAnimatted.draw(gc);
-		for(Dragon dragon: dragons) {
-			dragon.draw(gc);
+		for(DrawableSimulable entity: entities) {
+			entity.draw(gc);
 		}
 	}
 
 	public void simulate(double timeDelta) {
-		bulletAnimatted.simulate(timeDelta);
+		for(DrawableSimulable entity: entities) {
+			entity.simulate(timeDelta);
+			if (entity instanceof Collisionable) {
+				Collisionable thisCollinsable = (Collisionable) entity;
+				for(DrawableSimulable entity2 : entities) {
+					if (entity != entity2 && entity2 instanceof Collisionable) {
+						Collisionable thatCollinsable = (Collisionable) entity2;
+						if (thisCollinsable.intersects(thatCollinsable)) {
+							thisCollinsable.hitBy(thatCollinsable);
+							thatCollinsable.hitBy(thisCollinsable);
+						}
+					}
+				}
+			}
+		}
+		/*bulletAnimatted.simulate(timeDelta);
 		cannon.simulate(timeDelta);
+		
 		for(Dragon dragon: dragons) {
 			if (bulletAnimatted.overlaps(dragon)) {
 				dragon.hit();
 				bulletAnimatted.reload();
 			}
 			dragon.simulate(timeDelta);
-		}
+		}*/
 	}
 
 	public double getWidth() {