Game dev course, lesson 2: guess the number

Table of Contents

Before you start 🧭

✅ Finish lesson 0 and lesson 1 first—you will reuse input(), print(), and running a .py file.

✅ A grown-up nearby helps for the terminal and for reading errors if something surprises you.

✅ Install notes and uv tips live in the companion SETUP.md. Stuck? Reference code is under lessons/02-guess-the-number/solution/ in the companion lab repository.

🎯 Pro tip: type the small programs yourself. Your fingers learn the patterns.

Goals 🎯

By the end of this lesson you will:

• 🔁 Run a while loop until a win condition
• 🌿 Branch with if, elif, and else
• 🎲 Pick a random secret with random.randint
• 🔢 Turn text into a number with int(...) around input()

Why this is “game dev” 🎮

Big games repeat a core loop: read what the player did, decide what it means, update the world, show feedback—then do it again. Your guess-the-number program is a tiny version of that loop: read a guess, compare, print a clue, repeat until “you win.”

Mini project: secret number 🔮

You will build guess.py in your lesson folder. The computer picks a secret number; you guess until you get it.

Step 1 — pick a secret with random 🎲

Create guess.py. Add:

import random

secret = random.randint(1, 10)
print("I picked a secret number from 1 to 10.")

randint(1, 10) means “pick an integer including both ends.” Each run can pick a different secret.

Run the file once. You should see the message (you are not guessing yet). ✅

Step 2 — one guess as a number 🔢

input() always returns text (a string). Compare numbers, so convert:

import random

secret = random.randint(1, 10)
print("I picked a secret number from 1 to 10.")

guess_text = input("Your guess: ")
guess = int(guess_text)
print("You guessed:", guess)

int(...) turns text like "7" into the number 7.

Honest heads-up: if the player types letters or a blank line, int can crash with an error. For this lesson, type digits only (ask a grown-up to read the error if it happens). Later you can add friendlier checks as a stretch.

Step 3 — too low, too high, or just right 🌿

Add branching below your guess line:

if guess < secret:
    print("Too low!")
elif guess > secret:
    print("Too high!")
else:
    print("You got it!")

• if runs its block when the condition is true.
• elif (“else if”) tries the next condition when the ones above failed.
• else runs when none of the earlier conditions matched.

Try a wrong guess on purpose, then a correct guess. Does the message match?

Step 4 — loop until the win 🔁

Wrap the “ask + compare” part in a while loop:

import random

secret = random.randint(1, 10)
print("I picked a secret number from 1 to 10.")

while True:
    guess_text = input("Your guess: ")
    guess = int(guess_text)

    if guess < secret:
        print("Too low!")
    elif guess > secret:
        print("Too high!")
    else:
        print("You got it! Nice job.")
        break

while True means “keep going.” break means “stop the loop now”—we only break when the guess is correct.

Play a few rounds. Celebrate when you win. 🎉

Try this 🛠️

1. Change the range — use randint(1, 20) and update the printed message so the player knows the new high end.
2. Count guesses — make a variable like tries = 0, add 1 each loop, and print how many tries it took when they win.
3. Flavor text — rewrite “Too low!” / “Too high!” as silly taunts from a grumpy oracle (keep it kind and inclusive).

Stretch goals 🌟

1. Max tries — stop the game with a different message if the player uses too many guesses without finding the secret.
2. Play again — after a win (or loss), ask “Play again? (y/n)” and start a new secret when they say yes.
3. Safer input — if you are ready for a grown-up-assisted detour, wrap int(...) in try / except so bad typing prints a friendly “digits only” message instead of a scary traceback.

Recap 📝

• random.randint picks the secret.
• int(input(...)) turns the player’s text into a number for comparisons.
• if / elif / else choose the right feedback.
• while + break keep the game going until someone wins.

Next lesson (preview) 🔮

Next you will lean on strings and choices to build a small text adventure—menus, rooms, and story branches—still in the terminal, still very much “game shaped.”