add space invaders game tutorial

Author: x4nth055

README.md

@@ -313,6 +313,7 @@ This is a repository of all the tutorials of [The Python Code](https://www.thepy
     - [How to Create a Platformer Game in Python](https://www.thepythoncode.com/article/platformer-game-with-pygame-in-python). ([code](gui-programming/platformer-game))
     - [How to Make a Flappy Bird Game in Python](https://thepythoncode.com/article/make-a-flappy-bird-game-python). ([code](gui-programming/flappy-bird-game))
     - [How to Create a Pong Game in Python](https://thepythoncode.com/article/build-a-pong-game-in-python). ([code](gui-programming/pong-game))
+    - [How to Create a Space Invaders Game in Python](https://thepythoncode.com/article/make-a-space-invader-game-in-python). ([code](gui-programming/space-invaders-game))
 
 
 For any feedback, please consider pulling requests.

gui-programming/space-invaders-game/README.md

@@ -0,0 +1 @@
+# [How to Create a Space Invaders Game in Python](https://thepythoncode.com/article/make-a-space-invader-game-in-python)

gui-programming/space-invaders-game/alien.py

@@ -0,0 +1,39 @@
+import pygame
+
+from settings import BULLET_SIZE
+from bullet import Bullet
+
+class Alien(pygame.sprite.Sprite):
+	def __init__(self, pos, size, row_num):
+		super().__init__()
+		self.x = pos[0]
+		self.y = pos[1]
+
+		# alien info
+		img_path = f'assets/aliens/{row_num}.png'
+		self.image = pygame.image.load(img_path)
+		self.image = pygame.transform.scale(self.image, (size, size))
+		self.rect = self.image.get_rect(topleft = pos)
+		self.mask = pygame.mask.from_surface(self.image)
+		self.move_speed = 5
+		self.to_direction = "right"
+
+		# alien status
+		self.bullets = pygame.sprite.GroupSingle()
+
+
+	def move_left(self):
+		self.rect.x -= self.move_speed
+
+	def move_right(self):
+		self.rect.x += self.move_speed
+
+	def move_bottom(self):
+		self.rect.y += self.move_speed
+
+	def _shoot(self):
+		specific_pos = (self.rect.centerx - (BULLET_SIZE // 2), self.rect.centery)
+		self.bullets.add(Bullet(specific_pos, BULLET_SIZE, "enemy"))
+
+	def update(self):
+		self.rect = self.image.get_rect(topleft=(self.rect.x, self.rect.y))