Session 2: Space Battle Game – Part 1

Bringing in the Sprites

Readying the Rocketship

Make sure that the bullet sprite is selected, before writing the script.

Follow the steps below to write the script:

1. Drag and drop a when flag clicked block from the Events palette in the scripting area.
2. Adjust the rocket’s size by choosing set size to ()% block from the Looks palette. Set it to 40% of the original size.
3. Drag and drop a go to x:() y:() block from the Motion palette below the when flag clicked block. Set x as 0 and y as -140; this will be our Rocketship’s initial position.
   
4. This time, let’s add some music at the beginning of the game. First, add the start sound () block from the Sound palette.
   
5. Now, click on the Sounds tab; it is next to the Costumes tab in the Block palette. In the bottom-left corner, you will find the Choose a Sound button. Select Video Game 1 from the library.
6. To go back to writing the script, click on the Blocks tab. Now, from the drop-down of the start sound () block, choose Video Game 1.
   

Now comes the fun part! We are going to use the keyboard’s arrow keys and the space bar to control the actions of our Rocketship! For this, please follow the steps below -:

1. Drag and drop a forever block (below the script we have made up till now) from the Control palette.
2. Add an if () then block from the Control palette.
3. From the Sensing palette, drag and drop the key () pressed? block and select the left arrow from the drop-down.
4. From the Motion palette, add the move () steps block within the if () block. Write -5 within the move () steps block. Now, when you will press the Left arrow key, the Rocket will move left by 5 steps (That is: It will move -5 steps in the horizontal direction, along the x-axis). Isn’t this Awesome!!
   
5. Now let us add another if () block, then we will drag and drop the key () pressed block but this time, select right arrow from the drop-down, also add the move () steps block within the if () block.
6. Now, when you will press the Right arrow key on the keyboard, the Rocketship will go right by 5 steps
   (That is: It will move +5 steps in the horizontal direction, along the x-axis).
7. Creating Clones of Bullet: For this, we will add another if () block within the forever block, then we will drag and drop the key () pressed block in it, but this time, we will select space. Now go to the Control palette and add create clone of () block and select Bullet from the dropdown.This will help you create multiple bullets (clones of your bullet) later. Also, add wait () seconds block from the Control palette and write 0.1 inside it, so that your next bullet fires, after a wait of 0.1 seconds.
8. Below is the complete script:
   
9. Don’t forget to save your script by the name Space Battle Game (If in doubt, refer to the previous session).
10. Yayy! let us test the code we have written until now. Click on the green flag to start the script,  and press the left and right arrow keys to check the movement of your Rocketship.