Free GameMaker (GML) Cheat Sheet

📦 Variables

// instance variable (Create Event)
hp = 100;
move_speed = 4;

// global variable, accessible anywhere
globalvar score;
global.score = 0;

// local variable, this scope only
var dist = point_distance(x, y, target.x, target.y);

Use global. for values shared across all objects, like score or game state.

⚙️ Events

Create	Runs once when the instance is spawned
Step	Runs every frame logic, input, movement
Draw	Runs every frame drawing only
Collision	Runs when this instance touches another object
Destroy	Runs once when the instance is destroyed
Alarm[0]	Runs once when its countdown reaches 0

🏃 Movement

// direct speed/direction
direction = 90;
speed = 4;

// component speeds
hspeed = 3;
vspeed = -2;

// move toward a point smoothly
move_towards_point(target.x, target.y, 4);

// simple keyboard movement
hspeed = (keyboard_check(vk_right) - keyboard_check(vk_left)) * move_speed;

💥 Collision

if (place_meeting(x, y, obj_wall)) {
    // touching a wall at current position
    move_bounce_solid(true);
}

var hit = instance_place(x, y, obj_enemy);
if (hit != noone) {
    instance_destroy(hit);
}

if (collision_rectangle(x-16, y-16, x+16, y+16, obj_spike, false, true)) {
    hp -= 10;
}

🧱 Instances

// spawn a new instance on a layer
instance_create_layer(x, y, "Instances", obj_bullet);

// destroy this instance
instance_destroy();

// run code on every instance of a type
with (obj_enemy) {
    hp -= 5;
}

🎨 Drawing

// Draw Event
draw_sprite(spr_player, image_index, x, y);

draw_set_color(c_white);
draw_text(10, 10, "Score: " + string(global.score));

draw_set_color(c_red);
draw_rectangle(x-16, y-16, x+16, y+16, false);

🔁 Control Flow

if (hp <= 0) {
    instance_destroy();
} else if (hp < 20) {
    show_debug_message("Low HP!");
} else {
    show_debug_message("OK");
}

for (var i = 0; i < 5; i++) { }
while (ammo > 0) { ammo--; }

switch (state) {
    case "idle": sprite_index = spr_idle; break;
    case "run":  sprite_index = spr_run;  break;
    default: break;
}

🛠️ Common Patterns: Top-Down Movement + Shooting

// --- Create Event ---
move_speed = 4;
fire_rate = 20;
fire_timer = 0;

// --- Step Event ---
var mx = (keyboard_check(vk_right) - keyboard_check(vk_left));
var my = (keyboard_check(vk_down) - keyboard_check(vk_up));
hspeed = mx * move_speed;
vspeed = my * move_speed;

fire_timer -= 1;
if (mouse_check_button(mb_left) && fire_timer <= 0) {
    var ang = point_direction(x, y, mouse_x, mouse_y);
    var b = instance_create_layer(x, y, "Instances", obj_bullet);
    b.direction = ang;
    b.speed = 10;
    fire_timer = fire_rate;
}

// --- obj_bullet Collision Event with obj_enemy ---
instance_destroy(other);
instance_destroy(self);

GameMaker (GML) Cheat Sheet

📦 Variables

⚙️ Events

🏃 Movement

💥 Collision

🧱 Instances

🎨 Drawing

🔁 Control Flow

🛠️ Common Patterns: Top-Down Movement + Shooting

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