diff --git a/alien.bmp b/alien.bmp
new file mode 100644
index 0000000..e91ef54
Binary files /dev/null and b/alien.bmp differ
diff --git a/alien.py b/alien.py
new file mode 100644
index 0000000..865b4b8
--- /dev/null
+++ b/alien.py
@@ -0,0 +1,41 @@
+import pygame
+from pygame.sprite import Sprite
+
+
+class Alien(Sprite):
+    """A class to represent a single alien in the fleet."""
+
+    def __init__(self, ai_settings, screen):
+        """Initialize the alien, and set its starting position."""
+        super(Alien, self).__init__()
+        self.screen = screen
+        self.ai_settings = ai_settings
+
+        # Load the alien image, and set its rect attribute.
+        self.image = pygame.image.load(r'alien.bmp')
+        self.rect = self.image.get_rect()
+
+        # Start each new alien near the top left of the screen.
+        self.rect.x = self.rect.width
+        self.rect.y = self.rect.height
+
+        # Store the alien's exact position.
+        self.x = float(self.rect.x)
+
+    def check_edges(self):
+        """Return True if alien is at edge of screen."""
+        screen_rect = self.screen.get_rect()
+        if self.rect.right >= screen_rect.right:
+            return True
+        elif self.rect.left <= 0:
+            return True
+
+    def update(self):
+        """Move the alien right or left."""
+        self.x += (self.ai_settings.alien_speed_factor *
+                   self.ai_settings.fleet_direction)
+        self.rect.x = self.x
+
+    def blitme(self):
+        """Draw the alien at its current location."""
+        self.screen.blit(self.image, self.rect)
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diff --git a/alien_invasion.py b/alien_invasion.py
new file mode 100644
index 0000000..a6e69bc
--- /dev/null
+++ b/alien_invasion.py
@@ -0,0 +1,54 @@
+import pygame
+from pygame.sprite import Group
+
+from settings import Settings
+from game_stats import GameStats
+from scoreboard import Scoreboard
+from button import Button
+from ship import Ship
+import game_functions as gf
+
+
+def run_game():
+    # Initialize pygame, settings, and screen object.
+    pygame.init()
+    ai_settings = Settings()
+    screen = pygame.display.set_mode(
+        (ai_settings.screen_width, ai_settings.screen_height))
+    pygame.display.set_caption("Alien Invasion")
+
+    # Make the Play button.
+    play_button = Button(ai_settings, screen, "Play")
+
+    # Create an instance to store game statistics, and a scoreboard.
+    stats = GameStats(ai_settings)
+    sb = Scoreboard(ai_settings, screen, stats)
+
+    # Set the background color.
+    bg_color = (230, 230, 230)
+
+    # Make a ship, a group of bullets, and a group of aliens.
+    ship = Ship(ai_settings, screen)
+    bullets = Group()
+    aliens = Group()
+
+    # Create the fleet of aliens.
+    gf.create_fleet(ai_settings, screen, ship, aliens)
+
+    # Start the main loop for the game.
+    while True:
+        gf.check_events(ai_settings, screen, stats, sb, play_button, ship,
+                        aliens, bullets)
+
+        if stats.game_active:
+            ship.update()
+            gf.update_bullets(ai_settings, screen, stats, sb, ship, aliens,
+                              bullets)
+            gf.update_aliens(ai_settings, screen, stats, sb, ship, aliens,
+                             bullets)
+
+        gf.update_screen(ai_settings, screen, stats, sb, ship, aliens,
+                         bullets, play_button)
+
+
+run_game()
\ No newline at end of file
diff --git a/bullet.py b/bullet.py
new file mode 100644
index 0000000..c26ab2c
--- /dev/null
+++ b/bullet.py
@@ -0,0 +1,34 @@
+import pygame
+from pygame.sprite import Sprite
+
+
+class Bullet(Sprite):
+    """A class to manage bullets fired from the ship."""
+
+    def __init__(self, ai_settings, screen, ship):
+        """Create a bullet object, at the ship's current position."""
+        super(Bullet, self).__init__()
+        self.screen = screen
+
+        # Create bullet rect at (0, 0), then set correct position.
+        self.rect = pygame.Rect(0, 0, ai_settings.bullet_width,
+                                ai_settings.bullet_height)
+        self.rect.centerx = ship.rect.centerx
+        self.rect.top = ship.rect.top
+
+        # Store a decimal value for the bullet's position.
+        self.y = float(self.rect.y)
+
+        self.color = ai_settings.bullet_color
+        self.speed_factor = ai_settings.bullet_speed_factor
+
+    def update(self):
+        """Move the bullet up the screen."""
+        # Update the decimal position of the bullet.
+        self.y -= self.speed_factor
+        # Update the rect position.
+        self.rect.y = self.y
+
+    def draw_bullet(self):
+        """Draw the bullet to the screen."""
+        pygame.draw.rect(self.screen, self.color, self.rect)
\ No newline at end of file
diff --git a/button.py b/button.py
new file mode 100644
index 0000000..8250882
--- /dev/null
+++ b/button.py
@@ -0,0 +1,34 @@
+import pygame.font
+
+
+class Button():
+
+    def __init__(self, ai_settings, screen, msg):
+        """Initialize button attributes."""
+        self.screen = screen
+        self.screen_rect = screen.get_rect()
+
+        # Set the dimensions and properties of the button.
+        self.width, self.height = 200, 50
+        self.button_color = (0, 255, 0)
+        self.text_color = (255, 255, 255)
+        self.font = pygame.font.SysFont(None, 48)
+
+        # Build the button's rect object, and center it.
+        self.rect = pygame.Rect(0, 0, self.width, self.height)
+        self.rect.center = self.screen_rect.center
+
+        # The button message only needs to be prepped once.
+        self.prep_msg(msg)
+
+    def prep_msg(self, msg):
+        """Turn msg into a rendered image, and center text on the button."""
+        self.msg_image = self.font.render(msg, True, self.text_color,
+                                          self.button_color)
+        self.msg_image_rect = self.msg_image.get_rect()
+        self.msg_image_rect.center = self.rect.center
+
+    def draw_button(self):
+        # Draw blank button, then draw message.
+        self.screen.fill(self.button_color, self.rect)
+        self.screen.blit(self.msg_image, self.msg_image_rect)
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