Day 19: Game States

Create a Start Screen Sprite

Add a new sprite called Start Screen. In the costume editor, draw a large filled rectangle that covers most of the stage, then write your game’s title and “Click to Start” on top of it.

Add this code:

when green flag clicked
go to x: (0) y: (0)
show

when this sprite clicked
broadcast [start game v]
hide

When the green flag is clicked, the start screen appears. When the player clicks it, it broadcasts start game to every sprite and then hides itself.

Update the Player

The player should be hidden until the game starts. Update your player sprite’s code so that it listens for the start game broadcast before showing and allowing movement. The player should be hidden when the green flag is clicked, and only show and move after receiving the start game broadcast:

when green flag clicked
hide

when I receive [start game v]
set [score v] to (0)
set [lives v] to (3)
go to x: (0) y: (-140)
show
forever
  if <key [left arrow v] pressed?> then
    change x by (-7)
  end
  if <key [right arrow v] pressed?> then
    change x by (7)
  end
end

Update the Falling Object Clones

Your clone factories should only start spawning after the game begins. Remember, the game now begins when the broadcast message start game is received. On your falling object sprite, change the factory to listen for the broadcast:

when green flag clicked
hide

when I receive [start game v]
forever
  wait (pick random (0.5) to (1.5)) seconds
  create clone of [myself v]
end

Danger Clones

The dangerous falling objects should also only start after the game begins. Change the clone factory to start on when I receive [start game v] instead of when green flag clicked.

Test the Start Screen

Click the green flag. You should see the start screen. Click it — it disappears, your player shows up, and objects start falling.

Create a Game Over Screen

Add a new sprite called Game Over. In the costume editor, draw a large filled rectangle and write “Game Over” in big text. You can add “Click green flag to play again” below it.

Add this code:

when green flag clicked
hide

when I receive [game over v]
go to x: (0) y: (0)
show
stop [other scripts in sprite v]

Broadcast Game Over from Danger Clones

Update your Danger clone code so that touching the player costs one life, and the game ends only when lives runs out. Replace the old stop [all v] check with this:

when I start as a clone
go to x: (pick random (-200) to (200)) y: (180)
show
repeat until <(y position) < (-170)>
  change y by (-4)
  if <touching [Player v]?> then
    change [lives v] by (-1)
    if <(lives) < (1)> then
      broadcast [game over v]
    end
    delete this clone
  end
end
delete this clone

Stop Everything on Game Over

Each sprite needs to react to the game over broadcast. On the player sprite, add:

when I receive [game over v]
hide
stop [other scripts in sprite v]

On both the falling object and Danger sprites, add:

when I receive [game over v]
stop [other scripts in sprite v]
delete this clone

This stops the clone factories and removes any remaining clones from the screen.

Test the Full Flow

Green flag — start screen appears. Click it — game plays. Take hits from danger objects until lives drops to 0 — game over screen appears. Click the green flag again to restart.