diff --git a/src/GameState.cpp b/src/GameState.cpp
index 4cffbfd..e727d49 100755
--- a/src/GameState.cpp
+++ b/src/GameState.cpp
@@ -22,6 +22,10 @@ GameState::GameState(int numberOfRobots) {
 }
 
 GameState::~GameState(){
+    clearUnits();
+}
+
+void GameState::clearUnits(){
     for (Unit *unit: units)
         delete unit;
     units.clear();
@@ -63,6 +67,23 @@ void GameState::updateCrashes() {
     }
 }
 
+GameState &GameState::operator=(const GameState &other) {
+    if (this == &other)
+        return *this;
+
+    clearUnits();
+    for (const Unit *const unit : other.units)
+        units.push_back(unit->clone());
+    hero = other.hero;
+    return *this;
+}
+
+GameState::GameState(const GameState &other) : hero(other.hero) {
+    clearUnits();
+    for (const Unit *const unit : other.units)
+        units.push_back(unit->clone());
+}
+
 int GameState::countToBeJunked() const {
     int numberDestroyed = 0;
     for (const Unit *const unit: units)
diff --git a/src/GameState.h b/src/GameState.h
index 7b6d21e..f4a76f9 100755
--- a/src/GameState.h
+++ b/src/GameState.h
@@ -27,7 +27,8 @@ public:
 
     ~GameState();
 
-
+    GameState &operator=(const GameState &other);
+    GameState(const GameState &other);
     /*
      * Clear and redraw entire playing field
      */
@@ -84,6 +85,7 @@ private:
 
     // private helpers
     bool isEmpty(const Unit& unit) const;
+    void clearUnits();
 
 };
 
diff --git a/src/Hero.cpp b/src/Hero.cpp
index 311b024..8feda57 100755
--- a/src/Hero.cpp
+++ b/src/Hero.cpp
@@ -14,3 +14,6 @@ void Hero::draw(QGraphicsScene *scene) const {
                           UNIT_WIDTH, UNIT_HEIGHT), Qt::NoPen, QBrush(HERO_COLOR));
 }
 
+Unit *Hero::clone() const {
+    return new Hero(*this);
+}
diff --git a/src/Hero.h b/src/Hero.h
index 26c8b45..5db8360 100755
--- a/src/Hero.h
+++ b/src/Hero.h
@@ -12,11 +12,12 @@
 class Hero : public Unit {
 
 public:
+    Unit *clone() const override;
 
     /*
     * Draws this hero onto the given QGraphicsScene.
     */
-    void draw(QGraphicsScene *scene) const;
+    void draw(QGraphicsScene *scene) const override;
 
 };
 
diff --git a/src/Junk.cpp b/src/Junk.cpp
index cf75b8f..087d36f 100755
--- a/src/Junk.cpp
+++ b/src/Junk.cpp
@@ -19,3 +19,7 @@ bool Junk::isAlive() const { return false; }
 bool Junk::isToBeJunked() const { return false; }
 void Junk::doCrash() {}
 void Junk::moveTowards(const Point &) {}
+
+Unit *Junk::clone() const {
+    return new Junk(*this);
+}
diff --git a/src/Junk.h b/src/Junk.h
index 4b75fa7..4025f1e 100755
--- a/src/Junk.h
+++ b/src/Junk.h
@@ -12,7 +12,7 @@
 class Junk : public Unit {
 public:
     Junk(const Point& p): Unit(p){}
-
+    Unit *clone() const override;
     /*
     * Draws this junk onto the given QGraphicsScene.
     */
diff --git a/src/Robot.cpp b/src/Robot.cpp
index 0b76830..920d9aa 100755
--- a/src/Robot.cpp
+++ b/src/Robot.cpp
@@ -25,4 +25,6 @@ void Robot::draw(QGraphicsScene *scene) const {
                              JUNK_RADIUS, JUNK_RADIUS), QPen(), QBrush(ROBOT_COLOR));
 }
 
-
+Unit *Robot::clone() const{
+    return new Robot(*this);
+}
diff --git a/src/Robot.h b/src/Robot.h
index 2ce8b63..42ae0bf 100755
--- a/src/Robot.h
+++ b/src/Robot.h
@@ -13,7 +13,7 @@ class Robot : public Unit {
     bool toBeJunked = false;
 
 public:
-
+    Unit* clone() const override;
     /*
      * did not crash yet
      */
diff --git a/src/Unit.h b/src/Unit.h
index ce53e82..d40dbed 100755
--- a/src/Unit.h
+++ b/src/Unit.h
@@ -28,6 +28,8 @@ public:
 
     virtual ~Unit(){}
 
+    virtual Unit *clone() const = 0;
+
     /*
     * Return Point representation of Unit
     */