A Windows Paint Remake (Simple). UP/DOWN Arrow to adjust brush size. BACKSPACE to erase everything.

SuperGGPaint.py

import pygame


#Initialization
pygame.init()
print("> SuperGGPaint Debug Console")
print("")

#Defining colors
white = (255,255,255)
black = (0,0,0)
red = (255,0,0) #RGB
green = (0,155,0)
blue = (0,0,255)
cyan = (0,220,220)
mouse_black = (0,0,0,25)

#Display
display_size = (800,600)
display_width = display_size[0]
display_height = display_size[1]
gameDisplay = pygame.display.set_mode(display_size)
clock = pygame.time.Clock()

title = "SuperGGPaint"
pygame.display.set_caption(title)

font_size = 30
font = pygame.font.SysFont(None, font_size)

def img(brush_size, color, imglist):
    for XnY in imglist:
        pygame.draw.rect(gameDisplay, color, [XnY[0],XnY[1],brush_size,brush_size])


def appLoop():
    
    #Game Loop
    appExit = False
    
    #Defining Varibles
    brush_size = 10
    brush_color = black
    imgList = []
    mouseDown = False
    
    while not appExit: #Main Loop
        brush_pos_x = pygame.mouse.get_pos()[0]
        brush_pos_y = pygame.mouse.get_pos()[1]
        
        for event in pygame.event.get():
            #print(event)
            #print(pygame.mouse.get_pos()[1])
            if event.type == pygame.QUIT:
                appExit = True
            elif event.type == pygame.KEYDOWN:
                
                if event.key == pygame.K_UP:
                    brush_size += 5
                    print("Set brush size bigger!")
                elif event.key == pygame.K_DOWN:
                    brush_size -= 5
                    print("Set brush size smaller!")
                elif event.key == pygame.K_BACKSPACE:
                    imgList = []
            if event.type == pygame.MOUSEBUTTONDOWN:
                mouseDown = True
            elif event.type == pygame.MOUSEBUTTONUP:
                mouseDown = False
                    
                    

        #Drawing to gameDisplay
        gameDisplay.fill(white) #Drawing Background
        
        imgHead = []
        imgHead.append(brush_pos_x)
        imgHead.append(brush_pos_y)
        
        if mouseDown == True:
            imgList.append(imgHead)
        
        pygame.draw.rect(gameDisplay, brush_color, [brush_pos_x,brush_pos_y,brush_size,brush_size])
        img(brush_size, brush_color, imgList)

        pygame.display.update() #Updates Game
        
    pygame.quit()
    quit()

appLoop()