Designing a Simple Digital Game

Introduction

A digital game is more than pictures on a screen. It is a small system with a goal, rules, actions, challenges, and feedback. In this aiMOOC, you will learn how to design and build a simple game that another person can understand and enjoy.

You will use ideas from Game design, Computer programming, algorithms, Digital art, and Digital citizenship. The examples use Scratch, a block-based programming language made for creative projects. The design ideas also work in other beginner-friendly game tools.

By the end of the course, you should be able to:

Game concept: Explain the goal, player actions, rules, and win or end condition of a simple game.
Algorithm: Plan the steps a game follows.
Sprite: Use characters or objects that respond to player input.
Event-driven programming: Start actions when something happens, such as a key press or a click.
Variable: Keep track of changing information such as a score or timer.
Debugging: Test a game, find problems, and improve it.
Digital citizenship: Share work safely and give credit for media you use.

What Makes a Simple Game?

A good first game has a clear idea that can be explained in one or two sentences. For example: Move a basket to catch falling stars. Each star gives you one point. The game ends after thirty seconds. This idea already contains a player action, a challenge, a score rule, and an end condition.

When you plan your own game, think about six questions. What is the player trying to achieve? What can the player do? What rules control the game? What creates a challenge? How does the game show that something happened? How does the player know when the game is over?

A game should be small enough to finish. A one-screen catching, maze, collecting, or jumping game is usually a better first project than a huge adventure with many levels.

Start with a Paper Prototype

Before you code, draw a quick paper prototype. Sketch the screen, the player character, important objects, and any score or timer display. Then point to the drawing and explain what should happen when the player presses a key or touches an object.

A paper prototype is useful because changing a pencil drawing is faster than rebuilding a large program. It also helps you notice missing rules. If a friend asks, What happens when I miss the star? you have found a rule that needs an answer.

Meet the Scratch Workspace

In Scratch, a sprite is a programmable character or object. The Stage is the area where your game appears. A backdrop is the Stage background. Blocks are instructions that you join together to create scripts.

Look at the editor image. The block palette is on the left, the coding area is in the middle, and the Stage is on the right. A beginner game often uses blocks from Motion, Events, Control, Sensing, Looks, Sound, and Variables.

Sprites and Backdrops

Choose sprites that make the game easy to understand. If the player catches objects, one sprite can be the catcher and another can be the falling object. Avoid adding many characters that have no job.

A backdrop can show the setting and can also support the rules. A road, ocean, space scene, or sports field can help the player understand where movement should happen.

Remember that a game can be visually simple and still be fun. Clear controls and rules are more important than complicated artwork.

Turning a Game Idea into an Algorithm

An Algorithm is a clear sequence of steps for solving a problem or completing a task. A game contains several smaller algorithms working together.

For a simple catching game, the catcher algorithm could work like this:

Start when the green flag is clicked.
Keep checking which arrow key the player presses.
Move left when the left key is pressed.
Move right when the right key is pressed.
Keep the catcher near the bottom of the Stage.

The falling-object algorithm could work like this:

Start at a random place near the top.
Move downward again and again.
If the object touches the catcher, add to the score.
Return to the top after a catch or a miss.
Keep repeating until the game ends.

The important idea is that you plan behavior before worrying about every individual block.

Sequence, Events, and Loops

A sequence is an order of instructions. If the order is wrong, the game may behave differently from what you expected.

An event starts a script. Examples include clicking the green flag, pressing a key, clicking a sprite, or receiving a message.

A loop repeats instructions. Games use loops because they must keep checking for input, movement, collisions, and other changes while the player is playing.

Player Controls and Movement

Controls should feel predictable. For a first game, arrow keys are a good choice. You can also use the mouse or make a sprite react when it is clicked.

The Scratch Stage uses x and y positions. The x position changes when an object moves left or right. The y position changes when it moves up or down. You do not need difficult mathematics to begin; you can test small changes and watch what happens.

A useful design habit is to teach the controls on the opening screen. Short text such as Use the arrow keys to move helps the player begin without guessing.

Rules with Conditions and Sensing

A condition asks whether something is true. Games use conditions for rules such as these: if the star touches the basket, increase the score; if the player touches a hazard, lose a life; if the timer reaches zero, end the game; and if the player reaches the goal, show a success message.

In Scratch, Sensing blocks can detect touching, mouse position, keys, distance, and other information. Control blocks such as if and if else let your program choose what to do after a condition is checked.

This is how a game connects player actions to consequences.

Collision Detection

A collision happens when game objects meet. In a catch game, touching the target should usually produce clear feedback. The game state can change, the player can see a change, and the player may hear a sound.

For example, when the star touches the catcher, the score can increase, the star can move back to the top, and a short sound can play. These signals help the player understand that the catch counted.

Scores, Timers, and Variables

A Variable stores information that can change. In a game, a variable can store a score, number of lives, level, speed, or time.

For a score variable, use a simple pattern:

Set the score to zero when the game starts.
Change the score when the player completes a scoring action.
Show the score so the player can see progress.

A timer creates a clear end point. You might give the player thirty seconds to collect as many objects as possible. A lives variable creates a different kind of challenge because the game can continue until all lives are used.

Use only the variables your game needs. Too many numbers can make a simple game harder to understand.

Challenge, Fairness, and Difficulty

A game should be challenging enough to stay interesting but fair enough that the player can learn. Difficulty can change in many ways: objects can move faster, safe spaces can become smaller, or the player can have less time.

Do not make difficulty depend on surprise rules that were never explained. If touching a red wall removes a life, the player should have a reasonable chance to learn that rule.

You can also create difficulty levels. An easy mode could use slower objects, while a harder mode uses faster movement. Testing with real players will show whether your idea is fair.

Accessibility and Clear Design

A game is easier to use when important information is not shown only through color. You can combine color with shapes, words, patterns, or sounds. Text should be large enough to read, controls should be consistent, and important sounds should also have a visual sign when possible.

If your game uses fast movement, think about whether a slower mode would help more players take part. Good design gives players enough information to understand what is happening.

Feedback, Sound, and Polish

Feedback tells the player that the game noticed an action. A score can change after a successful catch. A sprite can briefly change costume after being hit. A sound can play after collecting an item. A message can appear when the game ends.

Sound should support the game rather than make it confusing. Short sound effects can mark important events. Background music can create mood, but it should not hide instructions or become unpleasant through constant restarting.

Visual polish can come after the rules and controls work. First make the game playable. Then improve costumes, backdrops, animations, and sound.

Testing and Debugging

Debugging means finding and fixing problems in a program. Game designers test many times because code that looks correct may behave differently when a player interacts with it.

A simple testing cycle is:

Play one small part of the game.
Notice what you expected and what actually happened.
Find the script connected to the problem.
Change one thing.
Test again.

Common problems include a score that does not reset, a sprite that moves too far, an object that never returns to the top, or a game-over rule that does not stop every script.

Ask a classmate to test without giving extra spoken instructions. If they cannot discover the controls or goal, the game may need clearer on-screen directions.

Build Example: Star Catcher

Here is one possible small project. You do not have to copy it exactly.

Game idea: Move a catcher left and right. Catch falling stars to earn points before time runs out.

Main parts:

Player sprite: A catcher controlled with the left and right arrow keys.
Target sprite: A star that falls from a random position at the top.
Score variable: Starts at zero and increases after a catch.
Timer: Ends the game after a set time.
Backdrop: Shows the setting and leaves the play area easy to see.

Player script idea: Start on the green flag, repeat movement checks, and change x position when an arrow key is pressed.

Star script idea: Start near the top, move downward in a loop, detect a collision with the catcher, increase the score, and return to a new random top position.

Ending idea: When time is up, stop scoring, show the final score, and display a short message such as Game over.

Once the basic version works, you can add one improvement at a time. You might add a bonus object, a miss penalty, a harder speed, or a second backdrop.

Safe and Responsible Creating

When you make and share a game, use your own work or media you are allowed to use. Give credit when a license or creator asks for it. Do not share private information such as your full home address, passwords, or personal contact details inside a public project.

Be respectful when you test another person's game. Useful feedback describes what happened and suggests a possible improvement. For example: I understood the goal, but I could not tell which key made the character jump. Could you add a control hint?

Interactive Tasks

Quiz: Test Your Knowledge

Diesen aiMOOC als Battle spielen

What should a simple game goal tell the player? (What the player is trying to achieve) (!Which computer the designer used) (!How many files are in the project) (!Which color the editor uses)

What is a sprite in Scratch? (A programmable character or object) (!A password for a game) (!A type of school timetable) (!A printed game rulebook)

What does an event do in a program? (Starts an action when something happens) (!Deletes every sprite automatically) (!Makes all artwork three dimensional) (!Turns every variable into text)

Why are loops useful in games? (They repeat actions and checks) (!They make rules unnecessary) (!They remove all player choices) (!They always end the game at once)

What can a variable store in a game? (A changing value such as a score) (!Only a background picture) (!Only a keyboard key) (!Only the game title)

What is collision detection used for? (Checking whether game objects meet) (!Choosing a project file name) (!Drawing a paper prototype) (!Changing the computer volume)

What is useful feedback after a successful catch? (A score change or clear sound) (!A hidden rule) (!An unrelated long message) (!A frozen control)

What is debugging? (Finding and fixing problems) (!Adding random rules) (!Copying a finished game) (!Avoiding all testing)

Why should a classmate test your game? (To reveal unclear rules or problems) (!To choose your password) (!To remove your score) (!To stop you from revising)

Which choice can make a game more accessible? (Use more than color for important information) (!Make every instruction tiny) (!Change controls without warning) (!Hide the goal from the player)

Memory Game

Sprite	A programmable character or object in the game
Backdrop	The visual background of the Stage
Variable	A place to store information that can change
Loop	A structure that repeats instructions
Event	Something that starts a script
Collision	A moment when game objects touch
Feedback	A signal that shows the result of an action
Debugging	Finding and fixing problems in a program

Drag and Drop

Match the correct terms.	Topic
Goal	What the player is trying to achieve
Control	How the player gives input
Condition	A check that can be true or false
Score	A changing value that shows points
Prototype	An early version used to test an idea

...

Crossword Puzzle

Sprite	What is a programmable character or object called in Scratch?
Variable	What stores information that can change during a game?
Collision	What happens when two game objects meet?
Debugging	What process means finding and fixing program problems?
Feedback	What tells the player that the game noticed an action?
Sequence	What is an ordered set of instructions called?

LearningApps

Cloze Text

A simple game needs a clear

so the player knows what to do. A programmable character or object in Scratch is called a

. A set of steps in a useful order is an

. An

can start a script when a key is pressed or the green flag is clicked. A

repeats instructions while the game is running. A

lets the program decide what to do when something is true. A changing score can be stored in a

. When game objects touch, the program can detect a

. Clear visual or sound

helps the player understand the result of an action. Finding and fixing problems in the program is called

.

Open-Ended Tasks

Easy

Game idea: Write two sentences that explain the goal of a small digital game and what the player controls.
Paper prototype: Draw one game screen on paper and label the player, the goal object, the score area, and the main control.
Control instructions: Create a short start-screen message that tells a new player exactly how to move or act.
Game feedback: Design three clear feedback signals for a catch, a miss, and the end of a game using words, pictures, movement, or sound.

Standard

Scratch project: Build a one-screen game with one player-controlled sprite and one object that moves automatically.
Score system: Add a score variable that resets at the start and changes only when the scoring rule is met.
Playtesting: Ask a classmate to play your game without spoken help, record two moments of confusion or success, and revise one part.
Game tutorial video: Record a short screen video that demonstrates the goal, controls, scoring rule, and ending of your game.

Advanced

Difficulty balancing: Create two difficulty settings by changing speed, time, or another rule, then compare how each version feels to testers.
Accessibility review: Check whether your game gives important information through more than color and whether text and controls are easy to understand, then make two improvements.
Game design interview: Interview a player about what felt clear, fair, difficult, and fun, then turn the answers into a short improvement plan.
Game remix project: Create a new version of your game with one additional mechanic such as a bonus object, hazard, lives system, or second level, and explain how the new rule changes strategy.

Learning Assessment

Rule explanation: Explain how the goal, controls, scoring rule, and end condition work together to create a complete game loop.
Algorithm analysis: Read a short game plan and identify where a sequence, event, loop, condition, and variable would be useful, giving a reason for each choice.
Bug diagnosis: A score keeps its old value when a new game starts; explain the likely design problem and propose a test that would show whether your fix works.
Fairness evaluation: Compare two versions of the same game with different speeds and decide which is fairer for a new player, using observations rather than guesses.
Player feedback revision: Use comments from a playtester to choose one change that improves clarity and one change that improves challenge, and justify both.
Transfer challenge: Take the design of a catching game and explain how its variables, conditions, feedback, and testing process could be reused in a maze or jumping game.

Evidence of Learning

Important evidence of learning includes:

Knowledge: You can explain goals, rules, sprites, events, loops, conditions, variables, collisions, feedback, and debugging in your own words.
Skills: You can turn a game idea into an algorithm, create basic controls, use conditions, track a score, and test a program.
Product: You can produce a small playable digital game with clear instructions, a working goal, and an ending.
Testing evidence: You can record feedback from another player and show at least one revision based on that feedback.
Communication: You can explain how your game works to another learner using clear game-design and programming vocabulary.
Transfer: You can reuse the same design ideas in a different type of game or another interactive program.
Responsibility: You can use media safely, protect personal information, and give credit when needed.

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