import pgzrun

TITLE = "Paf l'oiseau"
WIDTH = 400
HEIGHT = 708

titi = Actor('bird1', (75, 350))
bird = Actor('bird0', (75, 350))

def draw():
    screen.blit('background', (0, 0))
    titi.draw()
    bird.draw()

def update():
    titi.x += titi.speed
    bird.x += bird.speed

titi.speed = 3
bird.speed = 5

pgzrun.go()