Simple Multiplayer Python Game and Server

game.py

import pygame, sys
from pygame.locals import *
import pickle
import select
import socket

WIDTH = 400
HEIGHT = 400
BUFFERSIZE = 2048

screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption('Game')

clock = pygame.time.Clock()

sprite1 = pygame.image.load('images/BlueThing/BlueThing_front.png')
sprite2 = pygame.image.load('images/Ladette/Ladette_front.png')
sprite3 = pygame.image.load('images/TrashPanda/TrashPanda_front.png')
sprite4 = pygame.image.load('images/Tubby/Tubby_front.png')

serverAddr = '127.0.0.1'
if len(sys.argv) == 2:
  serverAddr = sys.argv[1]
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((serverAddr, 4321))

playerid = 0

sprites = { 0: sprite1, 1: sprite2, 2: sprite3, 3: sprite4 }

class Minion:
  def __init__(self, x, y, id):
    self.x = x
    self.y = y
    self.vx = 0
    self.vy = 0
    self.id = id

  def update(self):
    self.x += self.vx
    self.y += self.vy

    if self.x > WIDTH - 50:
      self.x = WIDTH - 50
    if self.x < 0:
      self.x = 0
    if self.y > HEIGHT - 50:
      self.y = HEIGHT - 50
    if self.y < 0:
      self.y = 0

    if self.id == 0:
      self.id = playerid

  def render(self):
    screen.blit(sprites[self.id % 4], (self.x, self.y))


#game events
#['event type', param1, param2]
#
#event types: 
# id update 
# ['id update', id]
#
# player locations
# ['player locations', [id, x, y], [id, x, y] ...]

#user commands
# position update
# ['position update', id, x, y]

class GameEvent:
  def __init__(self, vx, vy):
    self.vx = vx
    self.vy = vy

cc = Minion(50, 50, 0)

minions = []

while True:
  ins, outs, ex = select.select([s], [], [], 0)
  for inm in ins: 
    gameEvent = pickle.loads(inm.recv(BUFFERSIZE))
    if gameEvent[0] == 'id update':
      playerid = gameEvent[1]
      print(playerid)
    if gameEvent[0] == 'player locations':
      gameEvent.pop(0)
      minions = []
      for minion in gameEvent:
        if minion[0] != playerid:
          minions.append(Minion(minion[1], minion[2], minion[0]))
    
  for event in pygame.event.get():
    if event.type == QUIT:
    	pygame.quit()
    	sys.exit()
    if event.type == KEYDOWN:
      if event.key == K_LEFT: cc.vx = -10
      if event.key == K_RIGHT: cc.vx = 10
      if event.key == K_UP: cc.vy = -10
      if event.key == K_DOWN: cc.vy = 10
    if event.type == KEYUP:
      if event.key == K_LEFT and cc.vx == -10: cc.vx = 0
      if event.key == K_RIGHT and cc.vx == 10: cc.vx = 0
      if event.key == K_UP and cc.vy == -10: cc.vy = 0
      if event.key == K_DOWN and cc.vy == 10: cc.vy = 0

  clock.tick(60)
  screen.fill((255,255,255))

  cc.update()

  for m in minions:
    m.render()

  cc.render()

  pygame.display.flip()

  ge = ['position update', playerid, cc.x, cc.y]
  s.send(pickle.dumps(ge))
s.close()

server.py

import socket
import asyncore
import select
import random
import pickle
import time

BUFFERSIZE = 512

outgoing = []

class Minion:
  def __init__(self, ownerid):
    self.x = 50
    self.y = 50
    self.ownerid = ownerid

minionmap = {}

def updateWorld(message):
  arr = pickle.loads(message)
  print(str(arr))
  playerid = arr[1]
  x = arr[2]
  y = arr[3]

  if playerid == 0: return

  minionmap[playerid].x = x
  minionmap[playerid].y = y

  remove = []

  for i in outgoing:
    update = ['player locations']

    for key, value in minionmap.items():
      update.append([value.ownerid, value.x, value.y])
    
    try:
      i.send(pickle.dumps(update))
    except Exception:
      remove.append(i)
      continue
    
    print ('sent update data')

    for r in remove:
      outgoing.remove(r)

class MainServer(asyncore.dispatcher):
  def __init__(self, port):
    asyncore.dispatcher.__init__(self)
    self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
    self.bind(('', port))
    self.listen(10)
  def handle_accept(self):
    conn, addr = self.accept()
    print ('Connection address:' + addr[0] + " " + str(addr[1]))
    outgoing.append(conn)
    playerid = random.randint(1000, 1000000)
    playerminion = Minion(playerid)
    minionmap[playerid] = playerminion
    conn.send(pickle.dumps(['id update', playerid]))
    SecondaryServer(conn)

class SecondaryServer(asyncore.dispatcher_with_send):
  def handle_read(self):
    recievedData = self.recv(BUFFERSIZE)
    if recievedData:
      updateWorld(recievedData)
    else: self.close()

MainServer(4321)
asyncore.loop()

This server can not send more than 1 event, only position update works. I would send a reply to ping received from client, and it doesn't work.

if arr[0] == 'ping':
and so on, then I'm sending a reply using i.send(pickle.dumps(['pong', playerid])) and it does not work. Client does not receive it.

I had the same problem as zywek123.

The reason is that the server writes to the socket a second time before the client reads from the socket the first message. This means that the client reads multiple pickled objects at once and pickle.loads just returns the first object.
Fortunately concatenated pickled objects can be easily separated:
https://stackoverflow.com/a/61293678/7658204

When I run the app in the mac terminal on python 3.9.1, I get the error:

s.connect((serverAddr, 4321))
ConnectionRefusedError: [Errno 61] Connection refused

Is there a solution?

When I run the app in the mac terminal on python 3.9.1, I get the error:

s.connect((serverAddr, 4321))
ConnectionRefusedError: [Errno 61] Connection refused

Is there a solution?

You need to change the address to your local ip or your hoes machine name