Your First Game

Overview

This tutorial will guide you through making your first Godot Engine project. You will learn how the Godot Engine editor works, how to structure a project, and how to build a 2D game.

Note

This project is an introduction to the Godot Engine. It assumes that you have some programming experience already. If you’re new to programming entirely, you should start here: Scripting.

The game is called “Dodge the Creeps”. Your character must move and avoid the enemies for as long as possible. Here is a preview of the final result:

../../_images/dodge_preview.gif
Why 2D?
3D games are much more complex than 2D ones. You should stick to 2D until you have a good understanding of the game development process.

Project Setup

Launch Godot and create a new project. Then, download dodge_assets.zip - the images and sounds you’ll be using to make the game. Unzip these files in your new project folder.

Note

For this tutorial, we will assume you are already familiar with the Godot Engine editor. If you haven’t read Scenes and nodes, do so now for an explanation of setting up a project and using the editor.

This game will use “portrait” mode, so we need to adjust the size of the game window. Click on Project -> Project Settings -> Display -> Window and set Width to 480 and Height to 720.

Organizing the Project

In this project, we will make 3 independent scenes: Player, Mob, and HUD, which we will combine into the game’s Main scene. In a larger project, it might be useful to make folders to hold the various scenes and their scripts, but for this relatively small game, you can save your scenes and scripts in the root folder, which is referred to as res://. You can see your project folders in the Filesystem Dock in the upper left corner:

../../_images/filesystem_dock.png

Player Scene

The first scene we make defines the “Player” object. One of the benefits of creating a separate Player scene is that we can test it separately, even before we’ve created the other parts of the game.

Node Structure

To begin, click the “Add/Create a New Node” button and add an Area2D node to the scene.

../../_images/add_node.png

With Area2D we can detect other objects that overlap or run into the player. Change its name to Player. This is the scene’s “root” or top-level node. We can add additional nodes to the player to add functionality.

Before we add any children to the Player node, we want to make sure we don’t accidentally move or resize them by clicking on them. Select the player node and click the icon next to the lock - its tooltip says “Makes sure the objects children are not selectable.”

../../_images/lock_children.png

Save the scene (click Scene -> Save, or press Meta-s).

Note

In this project, we will be following the Godot Engine naming conventions. Classes (Nodes) use CapWords, variables and functions use snake_case, and constants use ALL_CAPS.

Sprite Animation

Click on the Player node and add an AnimatedSprite node as a child. The AnimatedSprite will handle the appearance and animations for our player. Notice that there is a warning symbol next to the node. An AnimatedSprite requires a SpriteFrames resource, which is a list of the animation(s) it can display. To create one, find the Frames property in the Inspector and click “<null>” -> “New SpriteFrames”. Next, in the same location, click <SpriteFrames> to open the “SpriteFrames” panel:

../../_images/spriteframes_panel.png

On the left is a list of animations. Click the “default” one and rename it to “right”. Then click the “Add” button to create a second animation named “up”. Drag the two images for each animation into “Animation Frames” side of the panel:

../../_images/spriteframes_panel2.png

The player images are a bit too large for the game window, so we need to scale them down. Click on the AnimatedSprite node and set the Scale property to (0.5, 0.5). You can find it in the Inspector under the Node2D heading.

../../_images/player_scale.png

Finally, add a CollisionShape2D as a child of the Player. This will determine the player’s “hitbox”, or the bounds of its collision area. For this character, a CapsuleShape2D gives the best fit, so next to “Shape” in the Inspector, click “<null>”” -> “New CapsuleShape2D”. Resize the shape to cover the sprite:

../../_images/player_coll_shape.png

Warning

Remember not to scale the shape’s outline! Only use the size handles (red) to adjust the shape!

When you’re finished, your Player scene should look like this:

../../_images/player_scene_nodes.png

Moving the Player

Now we need to add some functionality that we can’t get from a built-in node, so we’ll add a script. Click the Player node and click the “Add Script” button:

../../_images/add_script_button.png

In the script settings window, you can leave the default settings, just click “Create”:

../../_images/attach_node_window.png

Note

If this is your first time encountering GDScript please read Scripting first.

Start by declaring the member variables this object will need:

extends Area2D

export (int) var SPEED  # how fast the player will move (pixels/sec)
var velocity = Vector2()  # the player's movement vector
var screensize  # size of the game window

Using the export keyword on the first variable SPEED allows us to set its value in the Inspector. This can be very handy for values that you want to be able to adjust just like a node’s built-in properties. Click on the Player node and set the speed property to 400.

../../_images/export_variable.png

The _ready() function is called when a node enters the scene tree, so that’s a good time to find the size of the game window:

func _ready():
    screensize = get_viewport_rect().size

Now we can use the _process() function to define what the player will do. The _process() function is called on every frame, so we’ll use it to update elements of our game which we expect to be changing often. Here we’ll have it:

  • check for input
  • move in the given direction
  • play the appropriate animation.

First, we need to check the inputs - is the player pressing a key? For this game, we have 4 direction inputs to check. Input actions are defined in the Project Settings under “Input Map”. You can define custom events and assign different keys, mouse events, or other inputs to them. For this demo, we will use the default events that are assigned to the arrow keys on the keyboard.

You can detect whether a key is pressed using Input.is_action_pressed(), which returns true if it is pressed or false if it isn’t.

func _process(delta):
    velocity = Vector2()
    if Input.is_action_pressed("ui_right"):
        velocity.x += 1
    if Input.is_action_pressed("ui_left"):
        velocity.x -= 1
    if Input.is_action_pressed("ui_down"):
        velocity.y += 1
    if Input.is_action_pressed("ui_up"):
        velocity.y -= 1
    if velocity.length() > 0:
        velocity = velocity.normalized() * SPEED
        $AnimatedSprite.play()
    else:
        $AnimatedSprite.stop()

We check each input and add/subtract from the velocity to obtain a total direction. For example, if you hold right and down at the same time, the resulting velocity vector will be (1, 1). In this case, since we’re adding a horizontal and a vertical movement, the player would move faster than if it just moved horizontally.

We can prevent that if we normalize the velocity, which means we set its length to 1, and multiply by the desired speed. This means no more fast diagonal movement.

Tip

If you’ve never used vector math before (or just need a refresher) you can see an explanation of vector usage in Godot at Vector math. It’s good to know but won’t be necessary for the rest of this tutorial.

We also check whether the player is moving so we can start or stop the AnimatedSprite animation.

Now that we have a movement direction, we can update the player’s position and use clamp() to prevent it from leaving the screen:

position += velocity * delta
position.x = clamp(position.x, 0, screensize.x)
position.y = clamp(position.y, 0, screensize.y)

Tip

Clamping a value means restricting it to a given minimum/maximum range.

Click “Play the Edited Scene. (F6)” and confirm you can move the player around the screen in all directions.

Choosing Animations

Now that the player can move, we need to change which animation the AnimatedSprite is playing based on direction. We have a “right” animation, which should be flipped horizontally (using the flip_h property) for left movement, and an “up” animation, which should be flipped vertically (flip_v) for downward movement. Let’s place this code at the end of our _process() function:

if velocity.x != 0:
    $AnimatedSprite.animation = "right"
    $AnimatedSprite.flip_v = false
    $AnimatedSprite.flip_h = velocity.x < 0
elif velocity.y != 0:
    $AnimatedSprite.animation = "up"
    $AnimatedSprite.flip_v = velocity.y > 0

Play the scene again and check that the animations are correct in each of the directions. When you’re sure that movement is working correctly, add this line to _ready() so the player will be hidden when the game starts:

hide()

Preparing for Collisions

We want the player to detect when it is hit by an enemy, but we haven’t made any enemies yet! That’s OK because we’re going to use Godot’s signal functionality to make it work.

Add the following at the top of the script (after extends Area2d):

signal hit

This defines a custom signal called “hit” that we will have our player emit (send out) when it collides with an enemy. We will use the Area2D to detect the collision. Select the Player node and click the “Node” tab next to the Inspector to see the list of signals the player can emit:

../../_images/player_signals.png

Notice our custom “hit” signal is there as well! Since our enemies are going to be RigidBody2D nodes, we want the body_entered( Object body ) signal - that will be emitted when a body contacts the player. Click “Connect..” and then “Connect” again on the “Connecting Signal” window - we don’t need to change any of those settings. Godot will automatically create a function called _on_Player_body_entered in your player’s script.

Tip

When connecting a signal, instead of having Godot create a function for you, you can also give the name of an existing function that you want to link the signal to.

Add this code to the function:

func _on_Player_body_entered( body ):
    hide() # Player disappears after being hit
    emit_signal("hit")
    monitoring = false

Warning

Disabling the monitoring property of an Area2D means it won’t detect collisions. By turning it off, we make sure we don’t trigger the hit signal more than once. However, changing the property in the midst of an area_entered signal will result in an error, because the engine hasn’t finished processing the current frame yet.

Instead, you can defer the change, which will tell the game engine to wait until it’s safe to set monitoring to false. Change the line to this:

call_deferred("set_monitoring", false)

The last piece for our player is to add a function we can call to reset the player when starting a new game.

func start(pos):
    position = pos
    show()
    monitoring = true

Enemy Scene

Now it’s time to make the enemies our player will have to dodge. Their behavior will not be very complex: mobs will spawn randomly at the edges of the screen and move in a straight line (in a random direction), then despawn when they go offscreen.

We will build this into a Mob scene, which we can then instance to create any number of independent mobs in the game.

Node Setup

Click Scene -> New Scene and we’ll create the Mob.

The Mob scene will use the following nodes:

Don’t forget to set the children so they can’t be selected, like you did with the Player scene.

In the RigidBody2D properties, set Gravity Scale to 0 (so that the mob will not fall downward). In addition, under the PhysicsBody2D section in the Inspector, click the Mask property and uncheck the first box. This will ensure that the mobs do not collide with each other.

../../_images/set_collision_mask.png

Set up the AnimatedSprite like you did for the player. This time, we have 3 animations: “fly”, “swim”, and “walk”. Set the Playing property in the Inspector to “On” and adjust the “Speed (FPS)” setting as shown below. We’ll select one of these randomly so that the mobs will have some variety.

Like the player images, these mob images need to be scaled down. Set the AnimatedSprite‘s Scale property to (0.75, 0.75).

../../_images/mob_animations.gif

As in the Player scene, add a CapsuleShape2D for the collision. To align the shape with the image, you’ll need to set the Rotation Deg property to 90 under Node2D.

Enemy Script

Add a script to the Mob and add the following member variables:

extends RigidBody2D

export (int) var MIN_SPEED # minimum speed range
export (int) var MAX_SPEED # maximum speed range
var mob_types = ["walk", "swim", "fly"]

We’ll pick a random value between MIN_SPEED and MAX_SPEED for how fast each mob will move (it would be boring if they were all moving at the same speed). Set them to 150 and 250 in the Inspector. We also have an array containing the names of the three animations, which we’ll use to select a random one.

Now let’s look at the rest of the script. In _ready() we choose a random one of the three animation types:

func _ready():
    $AnimatedSprite.animation = mob_types[randi() % mob_types.size()]

Note

You must use randomize() if you want your sequence of “random” numbers to be different every time you run the scene. We’re going to use randomize() in our Main scene, so we won’t need it here. randi() % n is the standard way to get a random integer between 0 and n-1.

The last piece is to make the mobs delete themselves when they leave the screen. Connect the screen_exited() signal of the Visibility node and add this code:

func _on_Visible_screen_exited():
    queue_free()

That completes the Mob scene.

Main Scene

Now it’s time to bring it all together. Create a new scene and add a Node named Main. Click the “Instance” button and select your saved Player.tscn.

../../_images/instance_scene.png

Note

See Instancing to learn more about instancing.

Now add the following nodes as children of Main, and name them as shown (values are in seconds):

  • Timer (named MobTimer) - to control how often mobs spawn
  • Timer (named ScoreTimer) - to increment the score every second
  • Timer (named StartTimer) - to give a delay before starting
  • Position2D (named StartPosition) - to indicate the player’s start position

Set the Wait Time property of each of the Timer nodes as follows:

  • MobTimer: 0.5
  • ScoreTimer: 1
  • StartTimer: 2

In addition, set the One Shot property of StartTimer to “On” and set Position of the StartPosition node to (240, 450).

Spawning Mobs

The Main node will be spawning new mobs, and we want them to appear at a random location on the edge of the screen. Add a Path2D named MobPath as a child of Main. When you select the Path2D node you will see some new buttons appear at the top of the editor:

../../_images/path2d_buttons.png

Select the middle one (“Add Point”) and draw the path by clicking to add the points shown. To have the points snap to the grid, make sure “Snap to Grid” is checked. This option can be found under the “Snapping Options” button to the left of the “Lock” button. It appears as a series of three vertical dots.

../../_images/draw_path2d.gif

Important

Draw the path in clockwise order, or your mobs will spawn pointing outwards instead of inwards!

After placing point 4 in the image, click the “Close Curve” button and your curve will be complete.

Now that the path is defined, add a PathFollow2D node as a child of MobPath and name it MobSpawnLocation. This node will automatically rotate and follow the path as it moves, so we can use it to select a random position and direction along the path.

Main Script

Add a script to Main. At the top of the script we use export (PackedScene) to allow us to choose the Mob scene we want to instance.

extends Node

export (PackedScene) var Mob
var score

func _ready():
    randomize()

Drag the Mob.tscn from the “FileSystem” panel and drop it in the Mob property.

Next, click on the Player and connect the hit signal to the game_over function, which will handle what needs to happen when a game ends. We will also have a new_game function to set everything up for a new game:

func new_game():
    score = 0
    $Player.start($StartPosition.position)
    $StartTimer.start()

func game_over():
    $ScoreTimer.stop()
    $MobTimer.stop()

Now connect the timeout() signal of each of the Timer nodes. StartTimer will start the other two timers. ScoreTimer will increment the score by 1.

func _on_StartTimer_timeout():
    $MobTimer.start()
    $ScoreTimer.start()

func _on_ScoreTimer_timeout():
    score += 1

In _on_MobTimer_timeout() we will create a mob instance, pick a random starting location along the Path2D, and set the mob in motion. The PathFollow2D node will automatically rotate as it follows the path, so we will use that to select the mob’s direction as well as its position.

Note that a new instance must be added to the scene using add_child().

func _on_MobTimer_timeout():
    # choose a random location on the Path2D
    $MobPath/MobSpawnLocation.set_offset(randi())
    # create a Mob instance and add it to the scene
    var mob = Mob.instance()
    add_child(mob)
    # set the mob's direction perpendicular to the path direction
    var direction = $MobPath/MobSpawnLocation.rotation + PI/2
    # set the mob's position to the random location
    mob.position = $MobPath/MobSpawnLocation.position
    # add some randomness to the direction
    direction += rand_range(-PI/4, PI/4)
    mob.rotation = direction
    # choose the velocity
    mob.set_linear_velocity(Vector2(rand_range(mob.MIN_SPEED, mob.MAX_SPEED), 0).rotated(direction))

Important

In functions requiring angles, GDScript uses radians, not degrees. If you’re more comfortable working with degrees, you’ll need to use the deg2rad() and rad2deg() functions to convert between the two measures.

HUD

The final piece our game needs is a UI: an interface to display things like score, a “game over” message, and a restart button. Create a new scene, and add a CanvasLayer node named HUD (“HUD” stands for “heads-up display”, meaning an informational display that appears as an overlay, on top of the game view).

The CanvasLayer node lets us draw our UI elements on the layer above the rest of the game so that the information it displays doesn’t get covered up by any game elements like the player or the mobs.

The HUD displays the following information:

  • Score, changed by ScoreTimer
  • A message, such as “Game Over” or “Get Ready!”
  • A “Start” button to begin the game

The basic node for UI elements is Control. To create our UI, we’ll use two types of Control nodes: The Label and the Button.

Create the following children of the HUD node:

  • Label (named ScoreLabel)
  • Label (named MessageLabel)
  • Button (named StartButton)
  • Timer (named MessageTimer)

Note

Anchors and Margins Control nodes have a position and size, but they also have anchors and margins. Anchors define the origin, or the reference point for the edges of the node. Margins update automatically when you move or resize a control node. They represent the distance from the control node’s edges to its anchor. See Design interfaces with the Control nodes for more details.

Arrange the nodes as shown below. Click the “Anchor” button to set a Control node’s anchor:

../../_images/ui_anchor.png

You can drag the nodes to place them manually, or for more precise placement, use the following settings:

ScoreLabel

  • Anchor: “Center Top”
  • Margin:
    • Left: -240
    • Top: 0
    • Right: 240
    • Bottom: 100
  • Text: 0

MessageLabel

  • Anchor: “Center”
  • Margin:
    • Left: -240
    • Top: -200
    • Right: 240
    • Bottom: 60
  • Text: Dodge the Creeps!

StartButton

  • Anchor: “Center”
  • Margin:
    • Left: -60
    • Top: 70
    • Right: 60
    • Bottom: 150
  • Text: Start

The default font for Control nodes is very small and doesn’t scale well. There is a font file included in the game assets called “Xolonium-Regular.ttf”. To use this font, do the following for each of the three Control nodes:

  1. Under “Custom Fonts”, choose “New DynamicFont”
../../_images/custom_font1.png
  1. Click on the “DynamicFont” you just added, and under “Font Data”, choose “Load” and select the “Xolonium-Regular.ttf” file. You must also set the font’s Size. A setting of 64 works well.
../../_images/custom_font2.png

Now add this script to the HUD:

extends CanvasLayer

signal start_game

The start_game signal tells the Main node that the button has been pressed.

func show_message(text):
    $MessageLabel.text = text
    $MessageLabel.show()
    $MessageTimer.start()

This function is called when we want to display a message temporarily, such as “Get Ready”. On the MessageTimer, set the Wait Time to 2 and set the One Shot property to “On”.

func show_game_over():
    show_message("Game Over")
    yield($MessageTimer, "timeout")
    $StartButton.show()
    $MessageLabel.text = "Dodge the\nCreeps!"
    $MessageLabel.show()

This function is called when the player loses. It will show “Game Over” for 2 seconds, and then return to the game title and show the “Start” button.

func update_score(score):
    $ScoreLabel.text = str(score)

This function is called in Main whenever the score changes.

Connect the timeout() signal of MessageTimer and the pressed() signal of StartButton.

func _on_StartButton_pressed():
    $StartButton.hide()
    emit_signal("start_game")

func _on_MessageTimer_timeout():
    $MessageLabel.hide()

Connecting HUD to Main

Now that we’re done creating the HUD scene, save it and go back to Main. Instance the HUD scene in Main like you did the Player scene, and place it at the bottom of tree. The full tree should look like this, so make sure you didn’t miss anything:

../../_images/completed_main_scene.png

Now we need to connect the HUD functionality to our Main script. This requires a few additions to the Main scene:

In the Node tab, connect the HUD’s start_game signal to the new_game() function.

In new_game(), update the score display and show the “Get Ready” message:

$HUD.update_score(score)
$HUD.show_message("Get Ready")

In game_over() we need to call the corresponding HUD function:

$HUD.show_game_over()

Finally, add this to _on_ScoreTimer_timeout() to keep the display in sync with the changing score:

$HUD.update_score(score)

Now you’re ready to play! Click the “Play the Project” button. You will be asked to select a main scene, so choose Main.tscn.

Finishing Up

We’ve now completed all the functionality for our game. Below are some remaining steps to add a bit more “juice” and improve the game experience. Feel free to expand the gameplay with your own ideas.

Background

The default gray background is not very appealing, so let’s change its color. One way to do this is to use a ColorRect node. Make it the first node under Main so that it will be drawn behind the other nodes. ColorRect only has one property: Color. Choose a color you like and drag the size of the ColorRect so that it covers the screen.

You can also add a background image, if you have one, by using a Sprite node.

Sound Effects

Sound and music can be the single most effective way to add appeal to the game experience. In your game assets folder, you have two sound files: “House In a Forest Loop.ogg”, for background music, and “gameover.wav” for when the player loses.

Add two AudioStreamPlayer nodes as children of Main. Name one of them Music and the other DeathSound. On each one, click on the Stream property, select “Load” and choose the corresponding audio file.

To play the music, add $Music.play() in the new_game() function and $Music.stop() in the game_over() function.

Finally, add $DeathSound.play() in the game_over() function as well.

Particles

For one last bit of visual appeal, let’s add a trail effect to the player’s movement. Choose your Player scene and add a Particles2D node named Trail.

There are a very large number of properties to choose from when configuring particles. Feel free to experiment and create different effects. For the effect in the example, use the following settings:

../../_images/particle_trail_settings.png

You also need to create a Material by clicking on <null> and then “New ParticlesMaterial”. The settings for that are below:

../../_images/particle_trail_settings2.png

See also

See Particles2D for more details on using particle effects.

Project Files

You can find a completed version of this project here: https://github.com/kidscancode/Godot3_dodge/releases