Pygame - Source code of my game

This is one of my simple game developed by using pygame module. In this game I demonstrate a simple logic. I think this source code will give you the basic idea about the programming. If you are interested in game programming also you are a beginner in this field , then i am sure this code must be useful to you.

# Import a library of functions called 'pygame'
import pygame
import random

# Initialize the game engine
pygame.init()
black = [ 0, 0, 0]

#Colors used in this game
white = [255,255,255]
green=[0,255,0]

#set the music
music=pygame.mixer.Sound("song.wav") 

music.play()

#Specify the comments display on the screen after the game
basicfont=pygame.font.Font('freesansbold.ttf',32)
gameover=basicfont.render("GAME OVER",1,green)
gameoverrect=gameover.get_rect()

#Display the result on the screen
scoreboard=pygame.font.Font(None,32)

# Set the height and width of the screen
screen = pygame.display.set_mode([600, 500])
pygame.display.set_caption("Point collection")

#coordinates
x_coord=0
y_coord=250
clock = pygame.time.Clock()

#create lists
atkr=[]
point=[]
atkb=[]

# Loop 10 times and add a images in a random x,y position
for i in range(10):
    x=random.randrange(200,600)
    y=random.randrange(0,500)
    atkr.append([x,y])

for i in range(5):
    x=random.randrange(0,600)
    y=random.randrange(0,500)
    point.append([x,y])

for i in range(10):
    x=random.randrange(0,600)
    y=random.randrange(0,500)
    atkb.append([x,y])

#Loop until the user clicks the close button.
done=False
move_x=0
move_y=0
score=0

while done==False:
    music.play()
    for event in pygame.event.get(): # User did something
        if event.type == pygame.QUIT: # If user clicked close
            done=True # Flag that we are done so we exit this loop

        # Ketboard used to control the player in left,right,top and bottom
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                move_x=-3            
            if event.key == pygame.K_RIGHT:
                move_x= 3
            if event.key==pygame.K_UP:
                move_y=-3

        if event.key==pygame.K_DOWN:   
        move_y=3      

         
        if event.type==pygame.KEYUP:
            if event.key==pygame.K_LEFT:
                move_x=0

        if event.key==pygame.K_RIGHT:
                move_x=0
            if event.key==pygame.K_UP:
                move_y=0
            if event.key==pygame.K_DOWN:
        move_y=0   

                           
#Move the object according to the speed vector.
    x_coord=x_coord+move_x
    y_coord=y_coord+move_y
    screen.fill(black)

# Create player
    player=pygame.image.load("man.jpg").convert()
    screen.blit(player,[x_coord,y_coord])
    rect1=pygame.Rect(x_coord,y_coord,25,35)
    player.set_colorkey(black)

# Process each atkr in the list
    for i in range(len(atkr)):
        atkr_img=pygame.image.load("im.gif").convert()
        screen.blit(atkr_img,atkr[i])
        # Move the atkr left three pixel
        atkr[i][0]-=3
        if rect1.collidepoint(atkr[i][0],atkr[i][1]):
        score=score-1
            y=random.randrange(0,500)
            atkr[i][1]=y
            x=random.randrange(590,600)
            atkr[i][0]=x     
        # If the atkr has moved off the left of the screen
        if atkr[i][0] <0:
            # Reset it just right of the screen
            y=random.randrange(0,500)
            atkr[i][1]=y
            x=random.randrange(590,600)
            atkr[i][0]=x    

      
    # Go ahead and update the screen with what we've drawn.
    pygame.display.flip()

    # Process each point list elements
    for i in range(len(point)):
        point_img=pygame.image.load("b2-17.png").convert()
        screen.blit(point_img,point[i])

        # Move the point image down three pixel
        point[i][1]+=3
          if rect1.collidepoint(point[i][0],point[i][1]):
            score=score+1
            y=random.randrange(-500,-10)
            point[i][1]=y
            x=random.randrange(0,600)
            point[i][0]=x

        # If the image has moved off the bottom of the screen
        if point[i][1] > 500:
            # Reset it just above the top
            y=random.randrange(-500,-10)
            point[i][1]=y
            # Give it a new x position
            x=random.randrange(0,600)
            point[i][0]=x

    for i in range(len(atkb)):
        atkb_img=pygame.image.load("alien.png").convert()
        screen.blit(atkb_img,atkb[i])
        atkb_img.set_colorkey(white)
        # Move the image top three pixel
        atkb[i][1]-=3       
        if rect1.collidepoint(atkb[i][0],atkb[i][1]):
            score=score-1
            y=random.randrange(490,500)
            atkb[i][1]=y
            x=random.randrange(0,600)
            atkb[i][0]=x

        # If the imaged has moved off the top of the screen
        if atkb[i][1] <0:
            # Reset it to the new position
            y=random.randrange(490,500)
            atkb[i][1]=y
            x=random.randrange(0,600)
            atkb[i][0]=x
    screen.blit(scoreboard.render("score"+str(score),4,white),[40,40])

    # Go ahead and update the screen with what we've drawn.
    pygame.display.flip()   
    clock.tick(20)
    if score<-2:
        screen.blit(gameover,gameoverrect)
        pygame.display.flip()
        done=True  
pygame.quit ()

You can download the code from here. If you have any suggestion regarding my game, please inform me.
 Click  Pygame  to show more details about pygame and game development.