slither.py

import pygame as pg
import time, random
pg.init()

white = [255, 255, 255];black = [0, 0, 0];red = [255, 0, 0];green = [0, 155, 0];blue = [0, 0, 255];grey = [0, 255, 255] #Colors follow the RGB pattern

displayWidth, displayHeight = 800, 600 #Change this to change the dimensions of the screen
gameDisplay = pg.display.set_mode((displayWidth, displayHeight))
pg.display.set_caption("Slither") #Change the "Slither" to your wish

background = grey #Change the background color but make sure it is defined above.

gameDisplay.fill(background)
clock = pg.time.Clock()
pg.display.update()

def snake(snakeList, blockSize):
    for XnY in snakeList:
        pg.draw.rect(gameDisplay, blue, rect = [XnY[0], XnY[1], blockSize, blockSize])

def msgToScreen(msg, color, size, positions):
    if positions == "center":positions = [displayWidth // 2 - (len(msg) * size // 6), displayHeight // 2]
    font = pg.font.SysFont(None, size)
    text = font.render(msg, True, color)
    gameDisplay.blit(text, positions)

def gameLoop():
    snakeLength = 5 #Change this to change the starting length of the snake
    diff = 2;blockSize = 30 #Change blockSize to change to size of the snake and the apple
    score = 0 #Change score to change the starting score
    applePlacement = lambda : [random.randrange(blockSize*2, displayWidth - blockSize*2), random.randrange(blockSize*2, displayHeight - blockSize*2), blockSize*2//3, blockSize*2//3]
    curApplePlace = applePlacement()
    leadX = leadY = 200 #Change this to change the starting position of the snake
    pg.draw.rect(gameDisplay, blue, rect = [leadX, leadY, blockSize, blockSize]);pg.display.update()
    leadXChange = leadYChange = 0
    gameOn = True;gameOver = False
    FPS = 150 #change FPS to change the speed
    #NOTE:The higher the FPS the higher the CPU and RAM consumption
    snakeList = []

    while gameOn:
        for event in pg.event.get():
            if event.type == pg.QUIT:gameOn = False
            elif event.type == pg.KEYDOWN:
                if event.key == pg.K_LEFT:
                    leadXChange = -diff;leadYChange = 0
                if event.key == pg.K_RIGHT:
                    leadXChange = diff;leadYChange = 0
                if event.key == pg.K_UP:
                    leadYChange = -diff;leadXChange = 0
                if event.key == pg.K_DOWN:
                    leadYChange = diff;leadXChange = 0
                if event.key == pg.K_SPACE:gameOn = False       
                
        leadX += leadXChange;leadY += leadYChange
        if leadX + blockSize >= displayWidth or leadX <= 0 or leadY + blockSize >= displayHeight or leadY <= 0:gameOver = True

        gameDisplay.fill(background)
        pg.draw.rect(gameDisplay, red, rect =  curApplePlace)
        snakeList.append([leadX, leadY])

        if len(snakeList) > snakeLength:del snakeList[0]
        
        if snakeList.count(snakeList[-1]) != len(snakeList):
            for element in snakeList[:-1]:
                if element == snakeList[-1]:
                    gameOver = True

        snake(snakeList, blockSize)
        msgToScreen(f"Score: {score}", green, 30, [25, 25])    
        pg.display.update()

        if (leadX <= curApplePlace[0] <= leadX + blockSize and leadY <= curApplePlace[1] <= leadY + blockSize) or (leadX <= curApplePlace[0] + curApplePlace[2] <= leadX + blockSize and leadY <= curApplePlace[1] + curApplePlace[3] <= leadY + blockSize):
            score += 1
            if snakeLength > 100:snakeLength += 25
            elif snakeLength > 500:snakeLength += 50
            elif snakeLength > 1500:snakeLength += 80
            if snakeLength == 2000:FPS = 200
            else:snakeLength += 10
            curApplePlace = applePlacement()

        clock.tick(FPS)
        while gameOver:
            gameDisplay.fill(background)
            msgToScreen(f'Your score was {score}. Press "C" to continue and "Q" to quit', red, 40, "center")   
            pg.display.update()
            for event in pg.event.get():
                if event.type == pg.QUIT:gameOn = gameOver = False
                elif event.type == pg.KEYDOWN:
                    if event.key == pg.K_c:
                        gameLoop();gameOn = gameOver = False
                    elif event.key == pg.K_q:gameOn = gameOver = False
gameLoop()
pg.quit()