Introduction

In this project you’ll learn how to create a game, in which you have to match up coloured dots with the correct part of the controller.

Step 1: Creating a controller

Let’s start by creating a controller, that will be used to collect dots.

Activity Checklist

  • Open the ‘Catch the Dots’ Scratch project online at jumpto.cc/dots-go or download from jumpto.cc/dots-get and then open if you are using the offline editor.

    You should see a controller sprite:

    screenshot
    screenshot
  • Turn your controller to the right when the right arrow key is pressed:

        when flag clicked
        forever
            if <key [right arrow v] pressed?> then
                turn right (3) degrees
            end
        end
  • Test out your controller – it should spin to the right.

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Challenge: Spinning left

Can you make your controller spin to the left when the left arrow key is pressed?

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Step 2: Collecting dots

Let’s add some dots for the player to collect with their controller.

Activity Checklist

  • Create a new sprite called ‘red’. This sprite should be a small red dot.

    screenshot
    screenshot
  • Add this script to your ‘red’ dot sprite, to create a new dot clone every few seconds:

        when flag clicked
        hide
        wait (2) secs
        forever
            create clone of [myself v]
            wait (pick random (5) to (10)) secs
        end
  • When each clone is created, you want it to appear in one of the 4 corners of the stage.

    screenshot
    screenshot

    To do this, first create a new list called start positions and click the (+) to add in the values -180 and 180.

    screenshot
    screenshot
  • You can use these 2 list items to pick a random corner of the stage. Add this code to the ‘dot’ sprite, so that each new clone moves to a random corner and then slowly moves towards the controller.

        when I start as a clone
        go to x: (item (random v) of [start positions v]) y: (item (random v) of [start positions v])
        point towards [controller v]
        show
        repeat until <touching [controller v]?>
            move (1) steps
        end

    The code above chooses either -180 or 180 for the x and y positions, meaning that each clone starts in one corner of the stage.

  • Test your project. You should see lots of red dots appear in each corner of the screen, and move slowly towards the controller.

    screenshot
    screenshot
  • Create 2 new variables called lives and score.

  • Add code to your stage to set the lives to 3 and the score to 0 at the start of the game.

  • You need to add code to the end of your red dot’s when I start as a clone code, so that either 1 is added to the player’s score if the colours match, or 1 is taken from the player’s lives if the colours don’t match.

        move (5) steps
        if <touching color [#FF0000]?> then
            change [score v] by (1)
            play sound [pop v]
        else
            change [lives v] by (-1)
            play sound [laser1 v]
        end
        delete this clone
  • Add this code to the end of your stage’s script, so that the game ends when the player loses all of their lives:

        wait until <(lives) < [1]>
        stop [all v]
  • Test your game to make sure this code works as expected.

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Challenge: More dots

Duplicate your ‘red’ dot sprite twice, and name the two new sprites ‘yellow’ and ‘blue’.

screenshot
screenshot

Edit these sprites (including their code), so that each coloured dot has to match the correct colour on the controller. Remember to test your project, making sure you gain points and lose lives at the right times, and that your game isn’t too easy or too hard!

screenshot
screenshot

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Step 3: Increasing the difficulty

Let’s make the game get more difficult the longer the player survives, by slowly reducing the delay between dots appearing.

Activity Checklist

  • Create a new variable called delay.

  • On your stage, create a new script that sets the delay to a high number, and then slowly reduces the delay time.

        when flag clicked
        set [delay v] to (8)
        repeat until < (delay) = (2)>
            wait (10) secs
            change [delay v] by (-0.5)
        end

    Notice that this is very similar to how a game timer works!

  • Finally, you can use this delay variable in your red, yellow and blue dots’ scripts. Remove the code that waits a random number of seconds between creating clones, and replace it with your new delay variable:

        wait (delay) secs
  • Test your new delay variable, and see whether the delay between dots reduces slowly. Does this work for all 3 coloured dots? Can you see the value of the delay variable reducing?

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Challenge: Faster moving dots

Can you improve your game by adding a speed variable, so that the dots start off moving 1 step at a time, and steadily get faster and faster? This will work in a very similar way to the delay variable used above, and you can use this code to help you.

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Step 4: High score

Let’s save the high score, so that players can see how well they’re doing.

Activity Checklist

  • Create a new variable called high score.

  • Click on your stage, and create a new custom block called check high score.

    screenshot
    screenshot
  • Just before the end of the game, add in your new custom block.

    screenshot
    screenshot
  • Add code to your custom block to store the current score as the high score if it’s the highest score so far:

        define [check high score]
        if <(score) > (high score)> then
            set [high score v] to (score)
        end
  • Test the code you’ve added. Play your game to check whether the high score is updated correctly.

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Challenge: Improve your game!

Can you think of ways to improve your game? For example, you could create special dots that:

  • double your score;
  • slow down the dots;
  • hide all the other dots on the screen!

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Challenge: Game menu

Can you add a menu (with buttons) to your game? You could add an instructions screen, or a separate screen for showing the high score. If you need help with this, the ‘Brain Game’ project will help you.