Changed the items to static that was need to be.

src/include/intro.h

@@ -7,7 +7,7 @@ using namespace std;
 class Intro {
 public:
 
-  void mainIntro();
+  static void mainIntro();
 private:
   
 };

src/include/main.h

@@ -1,4 +1,5 @@
 #include <iostream>
 #include "intro.h"
 #include "title.h"
+#include <cstdlib>
 using namespace std;

src/include/sleep.h

@@ -8,6 +8,6 @@ using namespace std;
 
 class Sleep{
   public:
-    void delay(int milliseconds);
+    static void delay(int milliseconds);
-    void type(string text);
+    static void type(string text);
 };

src/include/title.h

@@ -6,5 +6,5 @@ class Title{
   private:
   protected:
   public:
-    void mainTitle();
+    static void mainTitle();
 };

src/intro.cpp

@@ -1,10 +1,12 @@
 #include "include/intro.h"
 
 void Intro::mainIntro(){
-  Sleep sleep;
   int time = 1000;
-  sleep.delay(time);
+  cout << endl;
-  sleep.type("The world didn't end with a bang. It ended with a groan.. and the scratching of death fingers against steel shutters.");
+  cout << endl;
-  sleep.delay(time);
+  Sleep::type("");
-  sleep.type("Pete used to sell shotgun, slug, and survival tips to deer hunters and doomsday preppers out of his rundown gun store ");
+  Sleep::delay(time);
+  Sleep::type("The world didn't end with a bang. It ended with a groan.. and the scratching of death fingers against steel shutters.");
+  Sleep::delay(time);
+  Sleep::type("Pete used to sell shotgun, slug, and survival tips to deer hunters and doomsday preppers out of his rundown gun store ");
 }

src/main.cpp

@@ -1,9 +1,8 @@
 #include "include/main.h"
 
 int main (){
-  Title title; 
+  system("clear");
-  title.mainTitle();
+  Title::mainTitle();
-  Intro intro;
+  Intro::mainIntro();
-  intro.mainIntro();
   return 0;
 }

src/title.cpp

@@ -3,18 +3,17 @@
 #include "include/sleep.h"
 
   void Title::mainTitle(){
-    Sleep sleep;
     int time = 700;
     cout << "███████╗██╗  ██╗ ██████╗ ████████╗ ██████╗ ██╗   ██╗███╗   ██╗    ██████╗ ███████╗████████╗███████╗" << endl;
-    sleep.delay(time);
+    Sleep::delay(time);
     cout << "██╔════╝██║  ██║██╔═══██╗╚══██╔══╝██╔════╝ ██║   ██║████╗  ██║    ██╔══██╗██╔════╝╚══██╔══╝██╔════╝" << endl;
-    sleep.delay(time);
+    Sleep::delay(time);
     cout << "███████╗███████║██║   ██║   ██║   ██║  ███╗██║   ██║██╔██╗ ██║    ██████╔╝█████╗     ██║   █████╗  " << endl;
-    sleep.delay(time);
+    Sleep::delay(time);
     cout << "╚════██║██╔══██║██║   ██║   ██║   ██║   ██║██║   ██║██║╚██╗██║    ██╔═══╝ ██╔══╝     ██║   ██╔══╝  " << endl;
-    sleep.delay(time);
+    Sleep::delay(time);
     cout << "███████║██║  ██║╚██████╔╝   ██║   ╚██████╔╝╚██████╔╝██║ ╚████║    ██║     ███████╗   ██║   ███████╗" << endl;
-    sleep.delay(time);
+    Sleep::delay(time);
     cout << "╚══════╝╚═╝  ╚═╝ ╚═════╝    ╚═╝    ╚═════╝  ╚═════╝ ╚═╝  ╚═══╝    ╚═╝     ╚══════╝   ╚═╝   ╚══════╝" << endl;
   }