Creating a Simple Game in Scratch

1. Creating a Simple Game in Scratch Barb Ericson Georgia Tech June 2008

2. Start up Scratch • Click on Scratch.exe

3. The Scratch Stage • The Scratch stage is 480 pixels wide and 360 pixels high. 180 -240 240 0,0 at the center of the stage -180

4. Delete the Cat • Right click on the cat and pick delete • Or click on the cat to select that sprite and then click on the scissors to delete it

5. Add the Baby • Click on the folder with a star in it • if you hover over it, it says "Choose new sprite from file"

6. Select the People Folder

7. Scroll to the Baby • Click on the baby and then OK

8. Resize Your Sprite! • You can make your sprite larger or smaller by using the “grow sprite” or “shrink sprite” icons. • You click on one of these icons, then click on your sprite until it is the size you’d like. shrink grow

9. Move the Baby • Select (click on the arrow and then on the baby) and click and drag the baby to the bottom of the window

10. Respond to Arrow Keys • Click on Control (orange) and then drag out "when space key pressed"

11. Respond to Right Arrow • Click on down arrow next to space and select right arrow • Click on Motion (blue) and drag out a "move 10 steps"

12. Change the move amount • Click on the 10 • it will highlight in blue • Type 5 and press enter

13. Respond to Left Arrow • Click on Control (orange) • Drag out a "when space key pressed" • Change "space" to "left arrow" • Click on Motion • Drag out a "move 10 steps" • Change it to -5 (to move left) • Try out the left and right arrow keys • Does the baby leave the window?

14. Paint a Ball • Click on the paint brush and star • It will say "Paint new sprite" if you hover over it

15. Use the Paint Editor • Click on the Ellipse tool

16. Select a Color

17. Draw the Ellipse • Click and drag to create the ellipse • Then click on "OK"

18. Move the ball to the top • Click and drag the ball to the top of the window

19. Make the Ball Fall • When the green flag is clicked we want the ball to start at the top and fall down • Click on Control (orange) • Drag out a "When green flag clicked"

20. Start the Ball • Click on Motion (blue) • Drag out go to x # y # • this will always start the ball at the current position • Drag out a "point in direction 90" • and change it to 180 (down)

21. Make the ball fall • Click on Control (orange) • drag out a "forever" • Click on Motion (blue) • drag out a "move 10 steps" • change it to 1 step • Try it out!

22. Catch the ball! • If the distance from the center of the ball to the baby is less than the half the size of the ball then it is caught • Let's track how many balls we have caught with a score

23. Track the score • When we start the game set the score to 0 • Click on Variables (red) • Click on Make a Variable • Name it score

24. Set score to 0 • Drag the forever down • Drag out a "set score to 0" • Notice the score showing on the window

25. Did we catch the ball? • From Control drag out an if • We will check if the distance to the baby is less than half the ball size • Click on Number (green) and drag out a "blank < blank"

26. Distance to baby • Click on Sensing (light blue) • Drag out a "distance to blank" • Change it to sprite1

27. Half the Size of the Ball • Click on Number • Drag out a "blank / blank" • From Looks drag out a size • Type on second blank and type 2

28. Increment the score • Click on Variables • drag out a "change score by 1" • Try it out! • is this what you expected?

29. Reset the ball • Once you catch the ball • move it back to the top of the window • this time to a random x value • between the left edge and right edge • Click on Motion and drag out a "go to x # y #"

30. Pick a random X value • Click on Number • drag out a "pick random 1 to 10" • drop on the x value • change the 1 to -235 and change 10 to 235 • change the y value to 161

31. Adding Losing • If the baby doesn't catch the ball it just gets stuck at the bottom of the screen • Let's tell the player that he or she lost

32. Add text sprite • Click on the Paint new sprite button • Click on the T for text • Move the square to where you want the text • Type You Lost!

33. Hide the sprite • Click on Control • drag out "when green flag clicked" • Click on Looks • drag out hide

34. Check if lost • If the ball hits the bottom of the window • the player has lost • Click on Control • drag out an if

35. Check if at bottom • Click on Numbers • Drag out a "blank < blank" • Click on Motion • drag out a "y position" • Click on the last blank • type in -175

36. Broadcast a message • Sprites communicate by passing messages • One sprite broadcasts the message • Other sprites can listen for it and react to it when they receive it • Click on Control • drag out "broadcast blank" • click on new – name it lost • add a stop script tile • to stop the forever loop

37. Receive Lost • Click on the text sprite • Click on Control • drag out "when I receive blank" • click on the down arrow and select lost • Click on Looks • drag out show • Click on Control • drag out stop all • to stop all scripts

38. Record a Sound • Click on the ball sprite • Click on the Sounds tab • Click the Record button • Click the red circle to start • Click the black square to stop • Play with the right arrow

39. Name the sound • Click in the sound name area and rename it

40. Play the Sound • Click on Sound • drag out "play sound pop" • drop after increment the score • change pop to yum

41. Add a Background • Click on stage • Click on the Backgrounds tab • Click on import • Select a new background

42. Create Instructions • Click on the Show Project Notes in the upper right corner • Add the author and instructions

43. Share your game • You can share your projects at the scratch web site • http://scratch.mit.edu • Click on the Share! button • You can also download other projects and see how they were created

44. Other Ideas • Add a sound when you lose • You may need to add a "stop script" to the script for the ball after you send the lost message • Only catch the ball in the baby's mouth • Add the ability to win • When you reach a certain score • Track the amount of time it takes as well • Speed up the ball over time • Add more sprites to catch • Add a sprite to avoid • killer sprite

45. Concept Summary • Variables • can hold values and can change value • Forever loops • repeat all the commands inside of them one at a time until the script is stopped • Conditionals – ifs • only execute the body of the if when the condition is true • Sprites can pass messages • and receive them • Sprites can react to events • like clicking the green flag and pressing the left or right arrow keys • Sprites can have several scripts, costumes, and sounds