Mini-Game — Rock, Paper, Scissors

By the end of this lesson you can:

• Import the random module and use random.randint() to pick a number.
• Map that random number to a "move" using if / elif / else.
• Decide the winner of a round by combining the player's and the computer's moves with and.

Over the last three lessons we taught Python to compare, combine, and choose. Today we put all of that together to build a game. But first — Python on its own is too predictable. If we hard-code the computer's move, the player wins every time. We need a way to make Python surprise us.

Think aloud: how could a program pick a different move each time you run it, even though the file never changes?

Part 1 · import — bring in a toolbox

The very first line of a file that uses random numbers is:

import random

That tells Python "go fetch the random toolbox so I can use its helpers". You only write it once, at the top of the file. Forgetting import random is the #1 reason beginners get a NameError: name 'random' is not defined.

Part 2 · random.randint() — roll a virtual die

random.randint(low, high) gives back a whole number between low and high, inclusive on both ends.

import random

roll = random.randint(1, 6)
print(roll)

Run the program again and you'll usually get a different number — that's the point. Notice the dot: random.randint means "the randint tool that lives inside the random toolbox".

Part 3 · From a number to a "move"

For Rock, Paper, Scissors we want one of three options. Roll a 1-to-3, then map the number to a string using if / elif / else — the exact pattern from PY-L1-08.

import random

n = random.randint(1, 3)
if n == 1:
    computer = "rock"
elif n == 2:
    computer = "paper"
else:
    computer = "scissors"

print("Computer chose:", computer)

Part 4 · The rules of the game

Rock blunts scissors. Scissors cut paper. Paper wraps rock. Anything else, and someone loses or it's a tie. That's three "you win" cases — and they each need two things to be true at once: your move and the computer's. That's our and from last lesson, doing real work.

player_wins = (player == "rock"     and computer == "scissors") \
           or (player == "paper"    and computer == "rock")     \
           or (player == "scissors" and computer == "paper")

The \ at the end of a line just means "this line continues on the next one". We use it here so the Boolean reads top-to-bottom like a little rulebook. (You could also write it as one long line — both work.)

We'll grow this game in four small phases. Type each phase, run it, then bolt on the next bit. Save the file as rps.py.

Phase 1 · Ask the player

Code

# rps.py — Rock, Paper, Scissors (Phase 1 of 4)

player = input("rock, paper or scissors? ")
print("You chose:", player)

Run it. Type rock. The program should reply You chose: rock. Nothing clever yet — just an echo.

Phase 2 · Let the computer pick

Code

# rps.py — Rock, Paper, Scissors (Phase 2 of 4)
import random

player = input("rock, paper or scissors? ")

n = random.randint(1, 3)
if n == 1:
    computer = "rock"
elif n == 2:
    computer = "paper"
else:
    computer = "scissors"

print("You chose:    ", player)
print("Computer chose:", computer)

Run it three times. The computer's move should change. If it doesn't, double-check that import random is at the top.

Phase 3 · Decide the result

Code (add after Phase 2's last print)

tie         = player == computer
player_wins = (player == "rock"     and computer == "scissors") \
           or (player == "paper"    and computer == "rock")     \
           or (player == "scissors" and computer == "paper")

print()
if tie:
    print("🤝 It's a tie!")
elif player_wins:
    print("🎉 You win!")
else:
    print("🤖 Computer wins!")

Run it a few times. Try every move. Make sure tying with the computer prints the tie message and not "computer wins".

Phase 4 · Be a little friendlier

Finally, add a personality. The computer can taunt or congratulate the player with one extra print() depending on the result.

Full file

# rps.py — Rock, Paper, Scissors (Phase 4 of 4)
import random

name   = input("What's your name? ")
player = input("rock, paper or scissors? ")

# Computer rolls a 1-2-3 and maps it to a move
n = random.randint(1, 3)
if n == 1:
    computer = "rock"
elif n == 2:
    computer = "paper"
else:
    computer = "scissors"

# Decide the result with Booleans
tie         = player == computer
player_wins = (player == "rock"     and computer == "scissors") \
           or (player == "paper"    and computer == "rock")     \
           or (player == "scissors" and computer == "paper")

# Show the moves
print()
print(name + " chose:    ", player)
print("Computer chose:", computer)
print()

# Pick a final message
if tie:
    print("🤝 Same move! Try again next time,", name + ".")
elif player_wins:
    print("🎉 Nice one,", name + " — you beat the computer!")
else:
    print("🤖 The computer wins this round,", name + ".")

One sample run (lines you type are bold):

Output

What's your name? <strong>Aisyah</strong>
rock, paper or scissors? <strong>paper</strong>

Aisyah chose:     paper
Computer chose: rock

🎉 Nice one, Aisyah — you beat the computer!

What every earlier lesson contributed

• L1-02 · print — showing the moves and result.
• L1-03 · variables — player, computer, n, tie, player_wins.
• L1-07 · input — asking for the player's move.
• L1-08 · if/elif/else — mapping n to a move and announcing the result.
• L1-09 · Booleans — tie and player_wins as stored Boolean variables.
• L1-10 · and / or — the three-line winning-rules Boolean.

Pick at least two of these and add them to rps.py. Run after each change.

if computer == "rock":
    computer_emoji = "🪨"
elif computer == "paper":
    computer_emoji = "📄"
else:
    computer_emoji = "✂️"
print("Computer chose:", computer, computer_emoji)

valid_move = player == "rock" or player == "paper" or player == "scissors"
if not valid_move:
    print("That's not a real move!")
else:
    # ... your existing result logic ...

mode = input("easy or normal? ")
if mode == "easy":
    computer = "scissors"
else:
    n = random.randint(1, 3)
    if n == 1:
        computer = "rock"
    elif n == 2:
        computer = "paper"
    else:
        computer = "scissors"

One import random at the top, one random.randint(1, 3) to pick a move, and a handful of if statements knit ten lessons into a tiny game. Every piece you've learned earned its place.