How to Make a Game Like Jetpack Joyride in Unity 2D – Part 3

Raising the Dead

Now you need a restart button in there.

You will need another new namespace in MouseController to reload the level. Open the script and add the following at the top:

using UnityEngine.SceneManagement;

Now add the following new public method:

public void RestartGame()
{
    SceneManager.LoadScene("RocketMouse");
}

This method should be self-explanatory. When the RestartGame method is called, you ask the SceneManager to load the RocketMouse scene, starting it from the beginning again.

You only want the button to be displayed once the player has died and hit the ground. Therefore, to interact with the button in code, you need to add a public instance variable for it.

public Button restartButton;

Finally, add the following code to the end of the FixedUpdate method:

if (isDead && isGrounded)
{
    restartButton.gameObject.SetActive(true);
}

Head back into Unity to create the Button. Select GameObject ▸ UI ▸ Button.

In the Inspector rename your new button to restartButton. The button should already be centered perfectly. However, for future reference this could have been achieved by selecting the Anchor Preset Box, Holding down Alt and Shift and hitting the center and middle grid square.

Let’s make the button a little bigger. Adjust the Width to 200 and the Height to 60.

The text in the button is a child element of the Button. In the Hierarchy click the disclosure triangle next to the restartButton and select the Text element.

Back in the Inspector, change the Text to "Tap to restart!" and adjust the Font Size to 24.

You don’t want the button displayed at the start of the game, so once again select the restartButton in the hierarchy and uncheck the checkbox beside the name in the Inspector. This will leave it in the scene, but in an inactive state.

Select the mouse to display the Mouse Controller script in the Inspector, and drag the restartButton from the Hierarchy to the Restart Button in Mouse Controller.

The final step is to tell the button what method to execute when it’s tapped. Select the resetButton in the Hierarchy and in the Button component in the Inspector, find the On Click () at the bottom. Click the + button and drag the mouse GameObject from the Hierarchy into the None (Object) box. The No Function dropdown should become active. Click on it and select MouseController ▸ RestartGame().

That should be it! Hit run and have a go. When the mouse hits a laser, the "tap to restart" button should appear, and selecting it should restart the game.

Adding Sound and Music

The game is deadly quiet. You will be amazed how much better it feels once you add some sound and music.

Hitting Laser Sound

Open the Prefabs folder in the Project view and select the laser Prefab.

In the Inspector, add an Audio Source component by clicking Add Component and selecting Audio ▸ Audio Source. Then open the Audio folder in the Project view and drag the laser_zap sound to the Audio Clip field.

Don’t forget to uncheck Play On Awake — otherwise the laser zap sound will be played right at the start of the game and give your player a fright!

This is what you should get:

Now open the MouseController script and add the following code to the beginning of the HitByLaser method:

if (!isDead)
{
    AudioSource laserZap = laserCollider.gameObject.GetComponent<AudioSource>();
    laserZap.Play();
}

When the mouse touches the laser, you get a reference to the laser’s collider in OnTriggerEnter2D. By accessing the gameObject property of laserCollider you then get the laser object itself. Then, you can access the Audio Source component, and make it play.

Run the scene; you will now hear a zap sound when the mouse hits any laser.

Collecting Coin Sound

While you could apply the same approach with coins, you'll be doing something a little bit different. Open the MouseController script and add the following instance variable:

public AudioClip coinCollectSound;

Scroll down to the CollectCoin method and add following line of code at the end of the method:

AudioSource.PlayClipAtPoint(coinCollectSound, transform.position);

Switch back to Unity and select the mouse GameObject in the Hierarchy. Drag the coin_collect sound from the Project view to the Coin Collect Sound field in the MouseController script.

Run the scene. Grab a coin and enjoy the resulting sound effect!

Jetpack and Footsteps Sounds

Next, you need to add the sound of the jetpack and the mouse's footsteps when it is running on the floor. This will be just a little bit different since the mouse will have to have two Audio Source components at once.

Adding Audio Sources

Select the mouse GameObject in the Hierarchy and add two Audio Source components. Drag footsteps from the Project view to the Audio Clip of the first Audio Source component. Then drag jetpack_sound to the Audio Clip field of the second Audio Source component.

Enable Play On Awake and Loop for both Audio Sources.

If you run the scene, you will hear both sounds playing all the time, independently of whether the mouse is flying or running on the floor. You'll fix this in code.

Switching Between Footsteps and Jetpack Sounds

Open the MouseController script and add the following two instance variables:

public AudioSource jetpackAudio;
public AudioSource footstepsAudio;

These will reference your newly created Audio Sources. Now add the AdjustFootstepsAndJetpackSound method:

void AdjustFootstepsAndJetpackSound(bool jetpackActive)
{
    footstepsAudio.enabled = !isDead && isGrounded;
    jetpackAudio.enabled = !isDead && !isGrounded;
    if (jetpackActive)
    {
        jetpackAudio.volume = 1.0f;
    }
    else
    {
        jetpackAudio.volume = 0.5f;
    }
}

This method enables and disables the footsteps and the jetpack Audio Source components. The footsteps sound is enabled when the mouse is not dead and on the ground. The jetpack sound is enabled only when the mouse is not dead and not on the ground.

In addition, this method also adjusts the jetpack volume so that it corresponds with the particle system.

Finally, add a call to AdjustFootstepsAndJetpackSound at the end of the FixedUpdate method:

AdjustFootstepsAndJetpackSound(jetpackActive);

Next you will need to assign references to the Audio Source components within the mouse GameObject to the footstepsAudio and jetpackAudio variables.