🧩

Project, Room & First Object

GameMaker’s building blocks: sprites, objects, rooms

Active

🎯

Goal for this step

Create the project and understand GameMaker’s core concepts.

1Install GameMaker (gamemaker.io), the free tier covers this whole series. New Blank project, name it Pong.
2The three building blocks: Sprites (images), Objects (things with behaviour), Rooms (levels containing instances of objects).
3Make a sprite: spr_paddle, 16×96, filled white (the built-in editor is fine).
4Make an object: obj_paddle, assign spr_paddle.
5Open Room1, set it 800×500 with a dark background, drag obj_paddle in near the left edge. Run (F5), your paddle exists in a window!

👨‍👧

Parent note: GameMaker’s free licence is enough for the entire series; it only limits some export platforms. GML is a friendly first "real" language, Undertale and Chicory shipped with it.

✏️

Fill in the Blanks

+15 XP

GameMaker’s three core assets are sprites, and rooms. A copy of an object placed in a room is called an . The run key is .

🧠

Knowledge Check

+15 XP

The difference between an object and an instance is…

ASpelling

BThe object is the blueprint; instances are copies living in the room, one obj_paddle, two paddles

CObjects are bigger

⚡

Events & Your First GML

Step events and keyboard_check

Locked

🎯

Goal for this step

Move the paddle with GML code in the Step event.

1Objects respond to Events: Create (born), Step (every frame, 60/s), Draw, collisions and more.
2In obj_paddle: Add Event → Step, and write the movement code below.
3keyboard_check is true while held; y is the built-in vertical position; clamp keeps it on screen in one call!
4GML reads like simple English-maths. Run it and slide the paddle.

obj_paddle · Step Event

// move with W and S
if (keyboard_check(ord("W"))) y -= 6;
if (keyboard_check(ord("S"))) y += 6;

// stay on screen (48 = half the paddle height)
y = clamp(y, 48, room_height - 48);

⌨️

Code Challenge

+20 XP

Complete the paddle movement and clamp:

obj_paddle · Step

if (keyboard_check(ord("W"))) y  6;
if (keyboard_check(ord("S"))) y += 6;
y = (y, 48, room_height - );

💡 Hint: W moves up (y shrinks). GML has a one-call min/max limiter. The margins are half the paddle height at each end.

🧠

Knowledge Check

+15 XP

The Step event runs…

AOnce when the game starts

BEvery frame, ~60 times per second, it IS the game loop, per object

COnly when a key is pressed

⚪

The Ball: hspeed & vspeed

Built-in motion and wall bouncing

Locked

🎯

Goal for this step

Launch a ball with built-in speed variables and bounce it.

1Make spr_ball (16×16 white square) and obj_ball.
2GameMaker objects have motion BUILT IN: set hspeed and vspeed in the Create event and the instance moves itself, no position code needed!
3Bounce off top/bottom in Step: if the ball is past an edge, flip vspeed.
4choose(-4, 4) is GML’s coin flip, a random serve direction each run.
5Drop obj_ball in the room centre and run: it flies and bounces.

obj_ball

/// Create Event
hspeed = choose(-4, 4);
vspeed = choose(-3, 3);

/// Step Event
if (y < 8 || y > room_height - 8) {
    vspeed = -vspeed;
}

✏️

Fill in the Blanks

+15 XP

GameMaker instances move themselves when and vspeed are set. A random pick between listed values uses (-4, 4).

🧠

Knowledge Check

+15 XP

Why does obj_ball move with NO movement code in Step?

AA bug

Bhspeed/vspeed are engine-integrated: GameMaker applies them to x/y automatically every frame

CThe room moves instead

💥

Collision Events & Spin

The visual event system meets rebound maths

Locked

🎯

Goal for this step

Bounce the ball off paddles with position-based spin.

1GameMaker’s superpower: add a Collision event to obj_ball targeting obj_paddle, the code runs exactly when they touch. No manual overlap tests!
2In it: reverse and slightly grow hspeed, and set vspeed from WHERE the ball hit (distance from paddle centre, the spin trick works in every engine).
3other refers to the paddle instance in the collision, other.y is ITS position.
4Make the second paddle: a child object or a duplicate with Up/Down keys.

obj_ball · Collision with obj_paddle

// reverse and speed up slightly
hspeed = -hspeed * 1.05;

// spin: hit position steers the rebound
vspeed = (y - other.y) / 12;

// never fully flat
if (vspeed == 0) vspeed = 1;

⌨️

Code Challenge

+20 XP

Add spin from the hit position:

Collision event

hspeed = -hspeed * ;
vspeed = (y - .y) / 12;

💡 Hint: The rally grows 5% per hit; the special keyword referring to the touched instance provides its y.

🧠

Knowledge Check

+15 XP

In a collision event, other means…

AAny random object

BThe specific instance you collided with, here, exactly which paddle got hit

CThe previous ball

🔢

Scoring & the Controller Object

Global variables and an invisible manager

Locked

🎯

Goal for this step

Track score with a controller object and serve after points.

1Create obj_game, no sprite! Invisible manager objects are a core GameMaker pattern.
2Its Create event: global.score_l = 0; global.score_r = 0;, global variables reachable from any object.
3In obj_ball’s Step: ball past the left edge → global.score_r++, reset ball to centre and re-serve; mirror for the right.
4obj_game gets a Draw GUI event drawing both scores big and centred.
5Drop obj_game in the room. Score away!

obj_game

/// Create Event
global.score_l = 0;
global.score_r = 0;

/// Draw GUI Event
draw_set_halign(fa_center);
draw_text_transformed(340, 30, string(global.score_l), 3, 3, 0);
draw_text_transformed(460, 30, string(global.score_r), 3, 3, 0);

✏️

Fill in the Blanks

+15 XP

Variables reachable from every object are prefixed . An invisible manager object like obj_game is a classic GameMaker pattern.

🧠

Knowledge Check

+15 XP

Why put score in a controller object instead of inside the ball?

ABalls cannot count

BThe ball resets/respawns, data that must OUTLIVE gameplay objects belongs in a persistent manager

CGUI events need it

🤖

AI & Game Over

A beatable computer and first-to-7

Locked

🎯

Goal for this step

Finish with an AI opponent and a win screen.

1obj_paddle_ai Step: chase the ball with a dead zone and a capped speed (slower than yours, flaws make fun, the universal AI lesson).
2instance_exists guards against the serve gap.
3obj_game Step: first to 7 → set global.winner and go to a game-over state (a room_goto to rm_gameover is the easiest GameMaker way!).
4rm_gameover: an object drawing the winner + "press R" (keyboard_check_pressed(ord("R")) → room_goto(rm_game), reset scores).
5Ship it. GameMaker made all the boring parts easy, that is why devs love it.

obj_paddle_ai · Step

if (instance_exists(obj_ball)) {
    var gap = obj_ball.y - y;
    if (abs(gap) > 12) {
        y += sign(gap) * 5;     // capped chase speed
    }
    y = clamp(y, 48, room_height - 48);
}

⌨️

Code Challenge

+20 XP

Write the dead-zoned AI chase:

obj_paddle_ai · Step

var gap = obj_ball.y - y;
if ((gap) > 12) {
    y += (gap) * 5;
}

💡 Hint: One function gives the distance size, the other gives just its direction (-1 or 1).

🧠

Knowledge Check

+15 XP

sign(gap) returns…

AThe gap squared

B-1, 0 or 1, pure direction, letting you cap chase speed at exactly 5

CThe paddle sprite

🎉🏆🎮✨🎉

Workshop Complete!

Objects, events and GML, the GameMaker way of thinking, learned on the perfect first game. Episode 2: gravity and platforms!

Total XP

Level

Best Streak

Accuracy

▶ Episode 2: Simple Platformer →
⭐ View My Progress & Certificates

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GameMaker Go!Pong in GML

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Pong in GML