PX_lastname_Frogger-Style - GameMaker Lesson

Project Name

Your GameMaker project must be named:

PX_lastname_Frogger-Style

Replace lastname with your own last name.

Example:

PX_Smith_Frogger-Style

Learning Objectives

By the end of this lesson, you should be able to:

Create a player object.
Move the player using the keyboard.
Create moving obstacle objects.
Organize obstacles into traffic lanes.
Make obstacles move at different speeds.
Make obstacles move in different directions.
Detect collisions between the player and obstacles.
Reset the player after a collision.
Create a goal area.
Detect when the player reaches the goal.
Track lives and score.
Create a level or win condition.

The Goal

You will create a game inspired by the classic PX_lastname_Frogger arcade game.

The player begins near the bottom of the screen and must move toward the top.

The player must cross several lanes filled with moving obstacles.

If the player touches an obstacle:

The player loses a life.
The player returns to the starting position.

If the player reaches the goal:

The player earns points.
The player may advance toward the next level.
Future levels can become more difficult.

The goal is to safely cross all lanes and reach the goal area.

Part 1 - Create the Project

Open GameMaker.
Create a new project.
Save the project using the required filename.

PX_lastname_Frogger-Style

Checkpoint 1:
Show your teacher that your project has been created and named correctly.

Part 2 - Create the Sprites

Create the following sprites:

Sprite	Purpose
spr_player	Player character
spr_car	Moving car obstacle
spr_truck	Larger moving obstacle
spr_goal	Goal area
spr_lane	Optional road or lane graphic

Suggested Sprite Sizes

Player: 32 × 32
Car: 64 × 32
Truck: 96 × 32
Goal: 64 × 32

Set the player sprite origin to Middle Center.

Part 3 - Create the Objects

Object	Sprite
obj_player	spr_player
obj_car	spr_car
obj_truck	spr_truck
obj_goal	spr_goal
obj_controller	No sprite

Part 4 - Create the Room

Create a room called:

rm_game

Suggested room size:

Width: 1024
Height: 768

The room should contain:

A safe starting area at the bottom.
Several traffic lanes in the middle.
A goal area at the top.

---------------------------------------
             GOAL AREA
---------------------------------------

<-- Cars moving left

--> Cars moving right

<-- Trucks moving left

--> Cars moving right

---------------------------------------
            START AREA
---------------------------------------

Your game should contain at least 4 traffic lanes.

Part 5 - Player Movement

Select:

obj_player

Add a Step Event.

var move_speed = 4;

if (keyboard_check(vk_left))
{
    x -= move_speed;
}

if (keyboard_check(vk_right))
{
    x += move_speed;
}

if (keyboard_check(vk_up))
{
    y -= move_speed;
}

if (keyboard_check(vk_down))
{
    y += move_speed;
}

Optional WASD Controls

You may also allow:

W = Up
A = Left
S = Down
D = Right

var move_speed = 4;

if (keyboard_check(vk_left) || keyboard_check(ord("A")))
{
    x -= move_speed;
}

if (keyboard_check(vk_right) || keyboard_check(ord("D")))
{
    x += move_speed;
}

if (keyboard_check(vk_up) || keyboard_check(ord("W")))
{
    y -= move_speed;
}

if (keyboard_check(vk_down) || keyboard_check(ord("S")))
{
    y += move_speed;
}

Part 6 - Keep the Player Inside the Room

Add this code to the player's Step Event:

x = clamp(x, sprite_width / 2, room_width - sprite_width / 2);
y = clamp(y, sprite_height / 2, room_height - sprite_height / 2);

The clamp() function prevents the player from moving outside the room.

Checkpoint 2:
Run the game and demonstrate that the player moves in four directions and stays inside the room.

Part 7 - Create Moving Cars

Select:

obj_car

Add a Create Event.

For a car moving from left to right:

hspeed = 4;

For a car moving from right to left:

hspeed = -4;

Understanding hspeed

hspeed controls horizontal movement.

Positive values move right.
Negative values move left.

Part 8 - Make Cars Wrap Around the Screen

Without wrapping, a car will leave the room and disappear.

Add a Step Event to obj_car.

if (x > room_width + sprite_width)
{
    x = -sprite_width;
}

if (x < -sprite_width)
{
    x = room_width + sprite_width;
}

The car will now reappear on the opposite side of the room.

Part 9 - Create Multiple Traffic Lanes

Place several car objects in each traffic lane.

Lane 1:   CAR --->      CAR --->

Lane 2:      <--- CAR       <--- CAR

Lane 3: TRUCK --->          TRUCK --->

Lane 4:      <--- CAR       <--- CAR

Each lane should have:

Different obstacle spacing.
Different speeds.
Different directions.

Part 10 - Different Lane Speeds

Slow lane:

hspeed = 2;

Medium lane:

hspeed = 4;

Fast lane:

hspeed = 6;

Use negative values for lanes moving toward the left.

hspeed = -5;

Part 11 - Create a Truck

Select:

obj_truck

Add a Create Event:

hspeed = -3;

Add a Step Event:

if (x > room_width + sprite_width)
{
    x = -sprite_width;
}

if (x < -sprite_width)
{
    x = room_width + sprite_width;
}

Trucks can be:

Larger than cars.
Slower than cars.
More difficult to avoid.

Part 12 - Save the Player's Starting Position

Select obj_player.

Add a Create Event:

start_x = x;
start_y = y;

These variables remember where the player started.

Part 13 - Player and Car Collision

In obj_player, add a Collision Event with:

obj_car

Enter:

global.lives -= 1;

x = start_x;
y = start_y;

When the player touches a car:

One life is lost.
The player returns to the starting position.

Part 14 - Player and Truck Collision

Add another Collision Event in obj_player with:

obj_truck

Enter:

global.lives -= 1;

x = start_x;
y = start_y;

Part 15 - Add Lives, Score, and Level

Create:

obj_controller

This object does not need a sprite.

Place one instance of obj_controller in the room.

Add a Create Event:

global.lives = 3;
global.score = 0;
global.level = 1;
global.goals_reached = 0;

Part 16 - Check for Game Over

Add a Step Event to obj_controller.

if (global.lives <= 0)
{
    show_message("GAME OVER");
    room_restart();
}

When the player's lives reach zero, the game restarts.

Part 17 - Create the Goal

Create:

obj_goal

Place the goal near the top of the room.

The player must safely cross the traffic lanes and touch the goal.

Part 18 - Detect the Goal

In obj_player, add a Collision Event with:

obj_goal

Enter:

global.score += 100;
global.goals_reached += 1;

x = start_x;
y = start_y;

The player receives 100 points each time the goal is reached.

Part 19 - Display Score, Lives, and Level

Select obj_controller.

Add a Draw GUI Event.

draw_text(20, 20, "Score: " + string(global.score));
draw_text(20, 50, "Lives: " + string(global.lives));
draw_text(20, 80, "Level: " + string(global.level));
draw_text(20, 110, "Goals: " + string(global.goals_reached));

The game will now display the player's score, lives, level, and completed goals.

Part 20 - Advance to the Next Level

Add this code to the Step Event of obj_controller.

if (global.goals_reached >= 3)
{
    global.level += 1;
    global.goals_reached = 0;

    show_message("LEVEL COMPLETE!");
}

The player must reach the goal three times to complete the level.

Part 21 - Make Higher Levels Harder

One way to increase difficulty is to make obstacles faster.

Example:

hspeed = 2 + global.level;

As the level number increases, the obstacle speed also increases.

You can also make higher levels harder by:

Adding more cars.
Adding more trucks.
Reducing the distance between obstacles.
Adding additional lanes.

Part 22 - Test Your Game

Your game should now contain:

Player movement.
Moving cars.
Moving trucks.
Multiple traffic lanes.
Different obstacle speeds.
Different obstacle directions.
Object wrapping.
Collision detection.
Lives.
Score.
Goal detection.
Level goals.

Debugging Checklist

Player Does Not Move

Make sure the movement code is in the player's Step Event.

keyboard_check()

Cars Do Not Move

Check the car Create Event.

hspeed = 4;

Cars Leave the Screen

Make sure the wrapping code is in the obstacle Step Event.

Collision Does Not Work

Check:

Collision masks.
Sprite sizes.
Collision Events.
Object names.

Player Does Not Return to Start

Verify the player Create Event contains:

start_x = x;
start_y = y;

Lives Do Not Change

Check the collision code:

global.lives -= 1;

Score Does Not Increase

Check the goal collision:

global.score += 100;

Required Features

Correct project filename.
Player-controlled movement.
At least 4 traffic lanes.
At least 2 different obstacle types.
Obstacles moving left.
Obstacles moving right.
Different lane speeds.
Object wrapping.
Player-obstacle collision detection.
Player reset after a collision.
Lives system.
Score system.
Goal area.
Goal detection.
Level or win condition.

Challenge 1 - Grid Movement

Make the player move one space at a time instead of moving continuously.

if (keyboard_check_pressed(vk_up))
{
    y -= 32;
}

Use similar code for left, right, and down.

Challenge 2 - Add Water

Add a river section near the top of the level.

The player loses a life if they enter the water without standing on a safe object.

Challenge 3 - Add Moving Logs

Create:

obj_log

Logs move across the water in the same way cars move across the road.

The player should be able to safely stand on the logs.

Challenge 4 - Ride on Moving Logs

Make the player move with a log while standing on it.

This introduces more advanced collision and movement programming.

Challenge 5 - Multiple Goal Spaces

Create several goal positions across the top of the room.

GOAL    GOAL    GOAL    GOAL    GOAL

Require the player to reach each goal location.

Challenge 6 - Increasing Difficulty

Increase difficulty by:

Increasing car speed.
Adding more cars.
Adding more trucks.
Reducing space between obstacles.
Adding more lanes.

Challenge 7 - Timer

Give the player a limited amount of time to reach the goal.

Display the remaining time on the screen.

Challenge 8 - Sound Effects

Add sound effects for:

Player movement.
Getting hit by a car.
Reaching the goal.
Losing a life.
Completing a level.

Vocabulary

Term	Definition
Sprite	The graphic representing an object.
Object	A GameMaker resource containing behavior.
Instance	A specific copy of an object placed in the game.
Lane	A horizontal area where obstacles travel.
Collision	When two objects touch.
Step Event	Code that repeatedly executes while the game runs.
Create Event	Code that executes when an object instance is created.
hspeed	Controls horizontal movement.
keyboard_check()	Checks whether a keyboard key is currently pressed.
keyboard_check_pressed()	Checks whether a key was just pressed.
clamp()	Restricts a value to a specified range.
Global Variable	A variable that can be accessed by multiple objects.
Goal	The destination the player must reach.
Level	A stage of the game.
Wrap	Moving an object from one edge of the room to the opposite edge.

Review Questions

What does hspeed control?
What is the difference between positive and negative hspeed?
Why do obstacles need screen wrapping?
What is the purpose of start_x and start_y?
What happens when the player collides with a car?
What is the purpose of global.lives?
How does the game detect that the player reached the goal?
Why should different traffic lanes have different speeds?
What are two ways to make higher levels more difficult?
What is the difference between keyboard_check() and keyboard_check_pressed()?

100-Point Grading Rubric

Requirement	Points
Correct filename PX_lastname_Frogger-Style	5
Room layout	5
Player sprite and object	5
Player movement	10
Player stays inside room	5
At least 4 traffic lanes	10
Moving cars	5
Second obstacle type	5
Obstacles move in both directions	5
Different obstacle speeds	5
Screen wrapping works	10
Collision detection works	10
Lives system	5
Score system	5
Goal detection and level condition	10
TOTAL	100

Final Checkpoint

Before submitting your assignment, demonstrate the game to your teacher.

Your teacher should see:

Player movement.
Multiple traffic lanes.
Moving obstacles.
Obstacles moving in both directions.
Different lane speeds.
Collision detection.
Player reset.
Lives changing.
Score increasing.
Goal detection.

Submission

Submit your GameMaker project according to your teacher's instructions.

Your project must be named:

PX_lastname_Frogger-Style

Before Submitting

Save your project.
Run the game one final time.
Make sure there are no error messages.
Confirm obstacles move correctly.
Confirm objects wrap around the room.
Confirm collisions work.
Confirm lives decrease.
Confirm the player can reach the goal.
Confirm the score increases.
Confirm the level goal works.

Final Goal

Create a working Frogger-Style Game that demonstrates:

Project Name

Learning Objectives

The Goal

Part 1 - Create the Project

Part 2 - Create the Sprites

Suggested Sprite Sizes

Part 3 - Create the Objects

Part 4 - Create the Room

Part 5 - Player Movement

Optional WASD Controls

Part 6 - Keep the Player Inside the Room

Part 7 - Create Moving Cars

Understanding hspeed

Part 8 - Make Cars Wrap Around the Screen

Part 9 - Create Multiple Traffic Lanes

Part 10 - Different Lane Speeds

Part 11 - Create a Truck

Part 12 - Save the Player's Starting Position

Part 13 - Player and Car Collision

Part 14 - Player and Truck Collision

Part 15 - Add Lives, Score, and Level

Part 16 - Check for Game Over

Part 17 - Create the Goal

Part 18 - Detect the Goal

Part 19 - Display Score, Lives, and Level

Part 20 - Advance to the Next Level

Part 21 - Make Higher Levels Harder

Part 22 - Test Your Game

Debugging Checklist

Player Does Not Move

Cars Do Not Move

Cars Leave the Screen

Collision Does Not Work

Player Does Not Return to Start

Lives Do Not Change

Score Does Not Increase

Required Features

Challenge 1 - Grid Movement

Challenge 2 - Add Water

Challenge 3 - Add Moving Logs

Challenge 4 - Ride on Moving Logs

Challenge 5 - Multiple Goal Spaces

Challenge 6 - Increasing Difficulty

Challenge 7 - Timer

Challenge 8 - Sound Effects

Vocabulary

Review Questions

100-Point Grading Rubric

Final Checkpoint

Submission

Before Submitting

Final Goal

Player Movement + Moving Obstacles + Traffic Lanes + Collision Detection + Lives + Level Goals