Conway's Game of Life

import pygame

WIDTH = 1000
HEIGHT = 720
TITLE = "CONWAY'S GAME OF LIFE"
TILESIZE = 20
FPS = 2
BACKGROUND = [20, 20, 20]   # default: [20, 20, 20]
GRID = [0, 0, 0]            # default: [0, 0, 0]
ORGANISM = [255, 255, 255]  # default: [255, 255, 255]

populated = []
unpopulated = []
location = []

i = 1

pygame.init()

RESOLUTION = [WIDTH, HEIGHT]
screen = pygame.display.set_mode(RESOLUTION)
pygame.display.set_caption(TITLE)

clock = pygame.time.Clock()


def event():

    global running

    for event in pygame.event.get():

        if event.type == pygame.QUIT:
            running = False

        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                running = False


def grid():

    for x in range(0, WIDTH, TILESIZE):
        pygame.draw.line(screen, GRID, (x, 0), (x, HEIGHT), 1)

    for y in range(0, HEIGHT, TILESIZE):
        pygame.draw.line(screen, GRID, (0, y), (WIDTH, y), 1)


def life(x, y):

    global populated

    X_TILESIZE = x * TILESIZE
    Y_TILESIZE = y * TILESIZE

    location = [X_TILESIZE, Y_TILESIZE]

    populated.append(location)

    del location


def death(location):

    global unpopulated

    unpopulated.append(location)

    del location


def factory():

    life(10, 10)
    life(10, 11)
    life(10, 12)

    life(20, 20)
    life(21, 20)
    life(22, 20)
    life(21, 19)
    life(20, 19)
    life(19, 19)

    life(38, 10)
    life(38, 11)
    life(38, 12)
    life(38, 13)
    life(38, 14)

    life(40, 10)
    life(40, 14)

    life(42, 10)
    life(42, 11)
    life(42, 12)
    life(42, 13)
    life(42, 14)


def render():

    global populated

    screen.fill(BACKGROUND)

    for organism in populated:

        pygame.draw.rect(screen, ORGANISM, (organism, [TILESIZE, TILESIZE]))

    grid()

    pygame.display.flip()


def duplication():

    global location
    global i

    duplicate = False

    if i == 1:
        death(location)
    else:
        for empty in unpopulated:
            if empty == location:
                duplicate = True
        if duplicate == False:
            death(location)
        duplicate = False


def rule():

    global unpopulated
    global populated
    global location
    global running
    global i

    unpopulated = []

    i = 1

    for organism in populated:

        numOfNeighbour = 0

        existR = False
        existL = False
        existU = False
        existD = False
        existCUR = False
        existCDR = False
        existCUL = False
        existCDL = False

        for neighbour in populated:

            if neighbour != organism:

                if neighbour[0] == organism[0] + TILESIZE and neighbour[1] == organism[1]:
                    numOfNeighbour += 1
                    existR = True

                elif neighbour[0] == organism[0] - TILESIZE and neighbour[1] == organism[1]:
                    numOfNeighbour += 1
                    existL = True

                elif neighbour[1] == organism[1] + TILESIZE and neighbour[0] == organism[0]:
                    numOfNeighbour += 1
                    existD = True

                elif neighbour[1] == organism[1] - TILESIZE and neighbour[0] == organism[0]:
                    numOfNeighbour += 1
                    existU = True

                elif neighbour[0] == organism[0] + TILESIZE and neighbour[1] == organism[1] - TILESIZE:
                    numOfNeighbour += 1
                    existCUR = True

                elif neighbour[0] == organism[0] + TILESIZE and neighbour[1] == organism[1] + TILESIZE:
                    numOfNeighbour += 1
                    existCDR = True

                elif neighbour[0] == organism[0] - TILESIZE and neighbour[1] == organism[1] - TILESIZE:
                    numOfNeighbour += 1
                    existCUL = True

                elif neighbour[0] == organism[0] - TILESIZE and neighbour[1] == organism[1] + TILESIZE:
                    numOfNeighbour += 1
                    existCDL = True

        if existR == False:
            location = [organism[0] + TILESIZE, organism[1]]
            duplication()

        if existL == False:
            location = [organism[0] - TILESIZE, organism[1]]
            duplication()

        if existU == False:
            location = [organism[0], organism[1] - TILESIZE]
            duplication()

        if existD == False:
            location = [organism[0], organism[1] + TILESIZE]
            duplication()

        if existCUR == False:
            location = [organism[0] + TILESIZE, organism[1] - TILESIZE]
            duplication()

        if existCDR == False:
            location = [organism[0] + TILESIZE, organism[1] + TILESIZE]
            duplication()

        if existCUL == False:
            location = [organism[0] - TILESIZE, organism[1] - TILESIZE]
            duplication()

        if existCDL == False:
            location = [organism[0] - TILESIZE, organism[1] + TILESIZE]
            duplication()

        i += 1

        if numOfNeighbour < 2 or numOfNeighbour > 3:
            organism.append("die")

    for empty in unpopulated:

        numOfNeighbour = 0

        for neighbour in populated:

            if neighbour[0] == empty[0] + TILESIZE and neighbour[1] == empty[1]:
                numOfNeighbour += 1

            elif neighbour[0] == empty[0] - TILESIZE and neighbour[1] == empty[1]:
                numOfNeighbour += 1

            elif neighbour[1] == empty[1] + TILESIZE and neighbour[0] == empty[0]:
                numOfNeighbour += 1

            elif neighbour[1] == empty[1] - TILESIZE and neighbour[0] == empty[0]:
                numOfNeighbour += 1

            elif neighbour[0] == empty[0] + TILESIZE and neighbour[1] == empty[1] - TILESIZE:
                numOfNeighbour += 1

            elif neighbour[0] == empty[0] + TILESIZE and neighbour[1] == empty[1] + TILESIZE:
                numOfNeighbour += 1

            elif neighbour[0] == empty[0] - TILESIZE and neighbour[1] == empty[1] - TILESIZE:
                numOfNeighbour += 1

            elif neighbour[0] == empty[0] - TILESIZE and neighbour[1] == empty[1] + TILESIZE:
                numOfNeighbour += 1

        if numOfNeighbour != 3:
            empty.append("empty")

    born = []

    for empty in unpopulated:
        if len(empty) == 2:
            born.append(empty)

    survive = []

    for organism in populated:
        if len(organism) == 2:
            survive.append(organism)

    populated = survive + born

    del unpopulated
    del survive
    del born


factory()

running = True
while running:

    clock.tick(FPS)
    event()
    render()

    if len(populated) == 0:
        running = False

    rule()