We've created a starter project that has some custom backdrops and sprites already setup. Open this starter project by clicking on the following link:

https://scratch.mit.edu/projects/291038023/editor

There are 3 backdrops included with this project, a 'title' backdrop to appear at the start of the game, a 'sea' backdrop to appear while you play the game and a 'game over' backdrop to appear when the game is finished.

Add the following code to the backdrop:

when green flag clicked switch backdrop to (title v) when I receive [start v] switch backdrop to (sea v) when I receive [gameover v] switch backdrop to (game over v)

Show: Scratch: How to create a message

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Messages are a great way to start a piece of code at a particular time. To create a new message follow these steps:

1. Add the broadcast [message 1 v] block to your code.
2. Click on the down arrow beside 'message 1' in the block.
3. Click on 'New message'.
4. Type in the name of your message. Give it a name that makes sense and you can remember it by.
5. Click the OK button.

When the instructions screen is showing, we also want to display a Start button that will start the game when the user clicks on it.

Add the following code to the 'Button2' sprite:

when green flag clicked show when this sprite clicked broadcast [start v] hide when I receive [gameover v] show

Now we will setup the 'battleship' sprite for the start of the game and code it to move when you press the left and right arrows. Add the following code to the 'battleship' sprite:

when green flag clicked set size to (50) % hide when I receive [start v] go to x (0) y (46) point in direction (90) switch costume to (battleship v) show forever if < key (right arrow v) pressed?> then change x by (5) end if < key (left arrow v) pressed?> then change x by (-5) end end

We're going to program the 'x' key to fire our torpedo when it is pressed. When fired, the torpedo will continually move down until it touches a submarine or the edge of the screen.

Add the following code to the 'my torpedo' sprite:

when [x v] key pressed create clone of (myself v) when I start as a clone switch costume to (normal v) go to (battleship v) // the torpedo needs to start at the same current location of your battleship show repeat until < touching (edge v)> if < touching (submarine v)> then switch costume to (hit v) // this is the explosion costume of the torpedo wait (0.2) secs delete this clone end change y by (-4) // move it down end delete this clone