In this add-on, you'll program an obstacle that slowly grows using the change size block.

To start, click on the obstacle sprite.

From Looks, drag out a change size by block.

Click this block a few times to make the obstacle sprite larger.

Use a forever block to make the obstacle keep growing.

Test your code by clicking the block stack.

That obstacle is really big.

To keep it from growing too large for your project, add a set size to block at the beginning of this block stack.

That way, the obstacle will start at its original size each time the stack is read.

Click the stack to test.

The obstacle grows way too fast.

The player will never make it past that.

Change the value in the change size block to something smaller, like one.

That's slower but it's still too fast.

Try changing the value to something smaller, like 0.3.

That's it, that's a much better speed.

Add a when flag clicked block to the top of the block stack to make your obstacle grow when the game begins.

Now it's your turn.

Make the obstacle grow and shrink using change size by, set size to, when flag clicked and forever blocks.

Choose an Add-On

Spinning Obstacle

Create a more challenging game by making an obstacle spin.


Create an obstacle that slowly grows throughout the game.


Program the goal sprite to chase the player sprite.

Keeping Time (Part 1 of 2)

Create a timer to keep score for this game, and program a way to store the fastest time.

Keeping Time (Part 2 of 2)

Create a timer to keep score for this game, and program a way to store the fastest time.

Redesign Your Maze

Change the look of the maze or draw your own!

Tell a Story

Engage game players with an exciting story for your game.


  1. Choose an Add-On, and click "watch" to learn how to build it.
  2. Once you finish one Add-On, try another one below the video!
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