Jumpstart Lab Curriculum


In this project you’ll use Ruby to build an implementation of the classic game Mastermind.


Learning Goals / Areas of Focus

  • Proficiently use TDD to drive development
  • Practice breaking a program into logical components
  • Learn to implement a REPL interface
  • Apply previously learned Enumerable techniques in a real context

Base Expectations

Use this repository as a template for your project.

You are to build a playable game of Mastermind that runs in a REPL interface.

Starting a Game

  • The player starts the game by running ruby mastermind.rb
  • Then they see:


Welcome to MASTERMINDWould you like to (p)lay, read the (i)nstructions, or (q)uit?>
  • If they enter p or play then they enter the game flow described below.
  • If they enter i or instructions they should be presented with a short explanation of how the game is played.
  • If they enter q or quit then the game should exit

Game Flow

Once the user starts a game they should see:


I have generated a beginner sequence with four elements made up of: (r)ed,(g)reen, (b)lue, and (y)ellow. Use (q)uit at any time to end the game.What's your guess?

They can then enter a guess in the form rrgb

  • Guesses are case insensitive
  • If it’s 'q' or 'quit' then exit the game
  • If it’s 'c' or 'cheat' then print out the current secret code
  • If it’s fewer than four letters, tell them it’s too short
  • If it’s longer than four letters, tell them it’s too long
  • If they guess the secret sequence, enter the end game flow below
  • Otherwise give them feedback on the guess like this:


'RRGB' has 3 of the correct elements with 2 in the correct positionsYou've taken 1 guess

Then let them guess again, repeating the game flow loop.

End Game

When the user correctly guesses the sequence, output the following:


Congratulations! You guessed the sequence 'GRRB' in 8 guesses over 4 minutes,22 seconds.Do you want to (p)lay again or (q)uit?

If they enter 'p' or 'play' then restart the game. 'q' or 'quit' ends the game.


If you’re able to finish the base expectations, add on one or more of the following extensions:

Difficulty Levels

When the user is getting ready to start a game, ask them what difficulty level they’d like to play with the following adaptations:

  • Beginner = 4 characters, 4 colors
  • Intermediate = 6 characters, 5 colors
  • Advanced = 8 characters, 6 colors

Record Tracking & Top 10

Use a file on the file system (like CSV, JSON, etc) to track completed games across runs of the program. When the user wins the game, output a message like this:


Congratulations! You've guessed the sequence! What's your name?> JeffJeff, you guessed the sequence 'GRRB' in 8 guesses over 4 minutes,22 seconds. That's 1 minute, 10 seconds faster and two guesses fewer than theaverage.=== TOP 10 ===1. Jeff solved 'GRRB' in 8 guesses over 4m22s2. Jeff solved 'BRGG' in 11 guesses over 4m45s3. Jorge solved 'BBBB' in 12 guesses over 4m15s4. Jorge solved 'GGBB' in 12 guesses over 5m12s

Note that they’re ranked first by number of guesses then by time.

Package & Polish

Your game won’t be very popular if it’s hard to install and run.

Add a Command Line Wrapper

Create an executable script that allows the user to just run mastermind from their terminal without directly executing Ruby.

Other Ideas

  • Add a history instruction to the gameplay which can be called before entering a guess and it’ll display all previous guesses and results in a compact form
  • Visual Interface - add colors and ASCII graphics to make a more compelling visual experience
  • Two-Player Mode - Add a game mode where players alternate guesses and whoever gets the sequence right first wins. Consider having their guesses hidden.

Evaluation Rubric

The project will be assessed with the following rubric:

1. Fundamental Ruby & Style

  • 4: Application demonstrates excellent knowledge of Ruby syntax, style, and refactoring
  • 3: Application shows some effort toward organization but still has 6 or fewer long methods (> 8 lines) and needs some refactoring.
  • 2: Application runs but the code has many long methods (>8 lines) and needs significant refactoring
  • 1: Application generates syntax error or crashes during execution

2. Test-Driven Development

  • 4: Application is broken into components which are well tested in both isolation and integration
  • 3: Application uses tests to exercise core functionality, but has some gaps in coverage or leaves edge cases untested.
  • 2: Application tests some components but has many gaps in coverage.
  • 1: Application does not demonstrate strong use of TDD

3. REPL Interface and Game Functionality

  • 4: Application’s REPL goes above and beyond expectations and application includes one or more extensions
  • 3: Application’s REPL is clear and pleasant to use and application fulfills base expectations from the project spec
  • 2: Application’s REPL has inconsistencies and/or there are errors in base gameplay
  • 1: Application’s REPL has several issues or application fails to run

4. Breaking Logic into Components

  • 4: Application effectively breaks logical components apart with clear intent and usage
  • 3: Application has multiple components with defined responsibilities but there is some leaking of responsibilities
  • 2: Application has some logical components but divisions of responsibility are inconsistent or unclear and/or there is a "God" object taking too much responsibility
  • 1: Application logic shows poor decomposition with too much logic mashed together

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