21 strategy game

21 Strategy Game

In this article, we will develop a game called 21 strategy game with the necessary algorithm and code.


The user and Computer will choose a number from 1 to 3. Whichever player reaches the total of 21 first, loses the game.


  1. Import the random module.
  2. Write a function to specify who wants to play the game first.
  3. If the user starts first get a number between 1-3 from the user and add it to the total. Now, change the current player to a computer.
  4. If the computer starts first get a random number between 1-3 and add it to the total. Now, change the current player to the user.
  5. Repeat steps 3 and 4 till the total becomes 21.
  6. Once we cross the total of 21 check who the current player is and announce the winner accordingly.

Program with explanation in comments

import random

def startPlayer(uName): 
  """Randomly selects who wants to play first"""
  player = random.randint(1,2)
  if player == 1:
    player = 'Ms. Computer'
    print('I will go first.')
    player = uName
    print('You will go first.')
  return player

def rules():

  """Displays the rules"""
  print('Welcome to the 21 Strategy Game! \nFirst, user and computer will choose a number from 1 to 3. Whichever player reaches the total 21 first, loses the game.')

def msComputer():

  """Generates a random number between 1 and 3 for computer's choice"""
  compNum = random.randint(1,3)
  return compNum

def user():

  """Gets the user input"""
  userNum = int(input('Choose a number from 1 to 3. '))
  if userNum<1 or userNum>3:
    print("Enter a valid number")
    return user()
    return userNum

def winning(otherP, uName):

  """This function is used to print the winner"""
  if otherP == 'Ms. Computer':
    print('Ms. Computer won! Better luck next time!')
    print(uName,'won! Good job!')

def gameStarts(uName):
  """This function is used to get the input from the user and computer till the number reaches 21 and returns the winner name"""

  total = 0 #initialize the total variable to 0
  rules()#display the rules
  firstP = startPlayer(uName) #randomly initialise the first player
  while total < 21: #repeat the game untill the total becomes 21
    if firstP == 'Ms. Computer':#if the current player was computer then we can call the function to get random number
      num = msComputer()
      total += num #increment the total by the taken number
      print('Ms. Computer (aka me) has chosen:',num)
      firstP = uName #change the current player to user
    else:#if the current player was user then we can call the function to get users input
      num = user()
      total += num#increment the total by the taken number
      print(uName,'(aka you) has chosen:',num)
      firstP = 'Ms. Computer' #change the current player to computer
    print('The total so far is:',total)
  return firstP #after coming out of the while loop we can return current player

#gets the player name 
userName = input('What is your name? ')
player = gameStarts(userName) #call the functionNumOutput and returns the player who won the game.
winning(player, userName)#calls the methodfor displaying who won the game.

Please note:

  • Recursion is the process of calling the same function inside the function definition. To know about recursion, recursion.
See also  Dictionary in python

A detailed explanation of the topics covered

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