View difference between Paste ID: mrWWdsMy and i61u0vPe

 #Space Invaders
 
 import os
 import turtle
 import math
 import random
 
 
 wn = turtle.Screen()
 wn.bgcolor("black")
 wn.title("Space Invaders")
 
 #Draw border
 border_pen = turtle.Turtle()
 border_pen.speed(0)
 border_pen.color("green")
 border_pen.penup()
 border_pen.setposition(-300,-300)
 border_pen.pendown()
 border_pen.pensize(3)
 for side in range(4):
     border_pen.fd(600)
     border_pen.lt(90)
 border_pen.hideturtle()
 
 #set score to 0
 score = 0
 
 #draw score
 score_pen = turtle.Turtle()
 score_pen.speed(0)
 score_pen.color("white")
 score_pen.penup()
 score_pen.setposition(-290, 280)
 scorestring = "Score: %s" %score
 score_pen.write(scorestring, False, align="left", font=("Arial", 14, "normal"))
 score_pen.hideturtle()
 
 
 #create player
 player = turtle.Turtle()
 player.color("purple")
 player.shape("triangle")
 player.penup()
 player.speed(0)
 player.setposition(0, -250)
 player.setheading(90)
 
 playerspeed = 25
 
 #choose number of enemies
 number_of_enemies = 5
 #create an empty list of enemies
 enemies = []
 
 #add enemies to list
 for i in range(number_of_enemies):
     #create the enemy
     enemies.append(turtle.Turtle())
 
 
 #create enemy
 for enemy in enemies:
     enemy.color("red")
     enemy.shape("circle")
     enemy.penup()
     enemy.speed(0)
     x = random.randint(-200, 200)
     y = random.randint(100, 250)
     enemy.setposition(x, y)
 
 enemyspeed = 2
 
 
 #create bullet
 bullet = turtle.Turtle()
 bullet.color("yellow")
 bullet.shape("triangle")
 bullet.penup()
 bullet.speed(0)
 bullet.setheading(90)
 bullet.shapesize(0.5, 0.5)
 bullet.hideturtle()
 
 bulletspeed = 20
 
 #define bullet state
 #ready - ready to fire
 #fire - bullet is firing
 bulletstate = "ready"
 
 
 
 
 
 #Move player left and right
 def move_left():
     x = player.xcor()
     x -= playerspeed
     if x < -280:
         x = - 280
     player.setx(x)
 
 def move_right():
     x = player.xcor()
     x += playerspeed
     if x > 280:
         x = 280
     player.setx(x)
 
 def fire_bullet():
     #declare bulletstate as global
     global bulletstate
     if bulletstate == "ready":
         bulletstate = "fire"
         #move bullet
         x = player.xcor()
         y= player.ycor() + 10
         bullet.setposition(x, y)
         bullet.showturtle()
 
 def isCollision(t1, t2):
     distance = math.sqrt(math.pow(t1.xcor()-t2.xcor(),2)+math.pow(t1.ycor()-t2.ycor(),2))
     if distance < 15:
         return True
     else:
         return False
 
 
 
 #create keyboard bindings
 turtle.listen()
 turtle.onkey(move_left, "Left")
 turtle.onkey(move_right, "Right")
 turtle.onkey(fire_bullet, "space")
 
 
 #maiin game loop
 while True:
     for enemy in enemies:
         #move enemy
         x = enemy.xcor()
         x += enemyspeed
         enemy.setx(x)
 
         #move enemy back and forth
         if enemy.xcor() > 280:
             for e in enemies:
                 y = e.ycor()
                 y -= 40
                 e.sety(y)
             enemyspeed *= -1
 
         if enemy.xcor() < -280:
             for e in enemies:
                 y = e.ycor()
                 y -= 40
                 e.sety(y)
             enemyspeed *= -1
 
         #check for a collision between the bullet and enemy
         if isCollision(bullet, enemy):
             #reset the bullet
             bullet.hideturtle()
             bulletstate = "ready"
             bullet.setposition(0, -400)
             #reset enemy
             x = random.randint(-200, 200)
             y = random.randint(100, 250)
             enemy.setposition(x, y)
             #Update score
             score += 10
             scorestring = "Score: %s" % score
             score_pen.clear()
             score_pen.write(scorestring, False, align="left", font=("Arial", 14, "normal"))
 
         if isCollision(bullet, enemy):
             bullet.hideturtle()
             bulletstate = "ready"
             bullet.setposition(0, -400)
             #reset enemy
             enemy.setposition(-200, 250)
 
         if isCollision(player, enemy):
             player.hideturtle()
             enemy.hideturtle()
             print ("Game Over Bitches!")
             break
 
 
     #move bullet
     if bulletstate == "fire":
         y = bullet.ycor()
         y += bulletspeed
         bullet.sety(y)
 
     #check to see if bullet has gone to top
     if bullet.ycor() > 275:
         bullet.hideturtle()
         bulletstate = "ready"
 
 turtle.done()
 dealy = input("Press Enter to finsih.")