A simple particle system.

from ion import *
from time import *
from random import *
from kandinsky import *

class Clock:
  def __init__(self):
    self.ltick=monotonic()
  def tick(self, target):
    ltick=self.ltick
    sleep((1/target)-(monotonic()-ltick))
    self.ltick=monotonic()
    return 1/(monotonic()-ltick)

size=2 #particle size
vx=0 #particle velocity along x
vy=-2 #particle velocity along y
x=100 #starting position along x
y=100 #starting position along y
disp=7 #dispersion around the starting position
rand=1 #randomization of movement
max_state=40 #number of steps
nb=6 #number of particles generated at each step
sensi=3
c=Clock()
particles=[]

while True:
  if True:
    if keydown(KEY_UP):
      y-=sensi
    elif keydown(KEY_DOWN):
      y+=sensi
    if keydown(KEY_LEFT):
      x-=sensi
    elif keydown(KEY_RIGHT):
      x+=sensi
  i=[]
  for _ in range(nb):
    particles+=[(
      x+randint(-disp,disp),
      y+randint(-disp,disp),
      0
      )]
  for p in range(len(particles)):
    xi,yi,s=particles[p]
    s+=1
    xi+=vx+randint(-rand,rand)
    yi+=vy+randint(-rand,rand)
    if s<max_state:
      i+=[(xi,yi,s)]
  particles=i
  fill_rect(0,0,330,230,(255,255,255))
  fill_rect(x-1,y+1,2,12,(0,0,0))
  fill_rect(x-6,y+9,12,50,(220,)*3)
  fill_rect(x-2,y-0,4,8,(255,150,0))
  for p in particles:
    fill_rect(int(p[0]),int(p[1]),size,size,(255-p[2]/max_state*200,)*3)
  c.tick(30) #target FPS