alien invasion game added

Alien-Invasion-Game

@@ -0,0 +1,161 @@
+import turtle
+import os
+import math
+import random
+
+
+wn=turtle.Screen()
+wn.bgcolor("black")
+wn.title("Space Invaders")
+
+border_pen=turtle.Turtle()
+border_pen.speed(0)
+border_pen.color("white")
+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()
+
+score=0
+
+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()
+
+
+player=turtle.Turtle()
+player.color("blue")
+player.shape("triangle")
+player.penup()
+player.speed(0)
+player.setposition(0,-250)
+player.setheading(90)
+
+playerspeed=15
+
+number_of_enemies=5
+enemies=[]
+
+for i in range(number_of_enemies):
+    enemies.append(turtle.Turtle())
+
+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
+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
+
+bulletstate="ready"
+
+def move_left():
+    x=player.xcor()
+    x-=playerspeed
+    if x<-180:
+        x=-280
+    player.setx(x)
+
+def move_right():
+    x=player.xcor()
+    x+=playerspeed
+    if x>280:
+        x=280
+    player.setx(x)
+
+def fire_bullet ():
+    global bulletstate
+    if bulletstate=="ready":
+        bulletstate="fire"
+        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
+
+turtle.listen()
+turtle.onkey(move_left, "Left")
+turtle.onkey(move_right, "Right")
+turtle.onkey(fire_bullet, "space")
+
+while True:
+
+    for enemy in enemies:
+        x=enemy.xcor()
+        x+=enemyspeed
+        enemy.setx(x)
+
+        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
+
+        if isCollision(bullet, enemy):
+            bullet.hideturtle()
+            bulletstate="ready"
+            bullet.setposition(0,-400)
+            x=random.randint(-200, 200)
+            y=random.randint(100, 250)
+            enemy.setposition(x, y)
+            score+=10
+            scorestring="Score:%s"%score
+            score_pen.clear()
+            score_pen.write(scorestring, False, align="left",font=("Arial", 14, "normal"))
+
+        if isCollision(player, enemy):
+            player.hideturtle()
+            enemy.hideturtle()
+            print("Game Over")
+            break
+
+    if bulletstate=="fire":
+        y=bullet.ycor()
+        y+=bulletspeed
+        bullet.sety(y)
+
+    if bullet.ycor()>275:
+        bullet.hideturtle()
+        bulletstate="ready"
+
+
+delay=raw_input("Press enter to finish")   
+
+
+