Morse Code Guess

What are we making?

Here's the finished game. Left: playing. Right: with the cheat sheet open.

Morse code in 1 minute

Morse code turns every letter into short and long beeps.

Our 13 letters, click one to hear it 🔊

Your school exercise is to spell SD ISLAMIC CENTER SAMARINDA KALIMANTAN TIMUR. Those words use only these 13 letters, so the game uses only these too.

1Get the files

Open Scratch (online or the Scratch app) and start a new project. Then download these files:

backdrop.svgStage backdrop lamp-off.svgLamp costume “off” lamp-on.svgLamp costume “on” replay-button.svgReplay Button cheat-button.svgCheat Button cheat-sheet.svgCheat Sheet 🔈1-dot.mp3Dot sound (0.1 s) 🔊2-line.mp3Dash sound (0.3 s) 🔤letters.txtFor the Letters list ·–codes.txtFor the Codes list

2Make the sprites

We need 5 sprites and a backdrop. Names matter! Type them exactly like this, because the code uses them.

1. Click the cat sprite and change its name from Sprite1 to Host.
2. Upload lamp-off.svg as a new sprite and name it Lamp. In its Costumes tab, upload lamp-on.svg too. Rename the costumes to off and on.
3. Still on the Lamp, open the Sounds tab and upload 1-dot.mp3 and 2-line.mp3. Delete the default sound if there is one.
4. Upload the two buttons and the cheat sheet, and name them as in the table.
5. Type the x and y numbers into the boxes under the stage for each sprite.
6. Click the Stage (bottom right), open Backdrops, upload backdrop.svg, and delete the white “backdrop1”.

3Variables & lists

Go to the orange Variables category. Use Make a Variable and Make a List.

For all sprites

Any sprite can use these, so pick “For all sprites” when you make them.

For this sprite only

First click the sprite, then make the variable with “For this sprite only”.

Fill the two lists

1. Make sure the checkbox next to Letters is ticked, so the list shows on the stage.
2. Right-click the list on the stage → import → choose letters.txt.
3. Do the same for Codes with codes.txt.
4. Check: item 1 of Letters is A and item 1 of Codes is .-. Item 11 is S and ...

What shows on the stage

Keep only Tries, Replays and Guesses ticked. Drag Tries and Replays to the top-right corner, and drag and resize the Guesses list to fill the right side (above the buttons). Untick Secret, or the answer shows on screen! 😄

4Lamp: the “play code” block

Our own block that plays one Morse code, like -.-.

1. Click the Lamp sprite. Go to My Blocks → Make a Block.
2. Type play code, then click Add an input (number or text) and name it code.
3. Leave “Run without screen refresh” unticked and click OK.
4. Build this under the pink define block. Drag the code input from the define block when you need it.

define play code (code)
set [symbol # v] to (1)
repeat (length of (code))
  switch costume to (on v)
  if <(letter (symbol #) of (code)) = [.]> then
    play sound (1-dot v) until done
  else
    play sound (2-line v) until done
  end
  switch costume to (off v)
  wait (0.1) seconds
  change [symbol # v] by (1)
end

How does it work?

symbol # is our pointer. It starts at 1 and moves one step each time round the loop. Here's what happens for the letter C (-.-.):

5Lamp: play all 3 letters

Still on the Lamp. First the start-up script:

when green flag clicked
switch costume to (off v)
set [Playing v] to (0)
set [letter gap v] to (1)

Now the script that plays the secret. In the when I receive dropdown, choose New message and call it play letters.

when I receive [play letters v]
set [Playing v] to (1)
set [letter # v] to (1)
repeat (length of (Secret))
  play code (item (item # of (letter (letter #) of (Secret)) in [Letters v]) of [Codes v]) :: custom
  wait (letter gap) seconds
  change [letter # v] by (1)
end
set [Playing v] to (0)

🧪 Test the lamp now!

Add this test script to the Lamp, then press space. You should hear and see ... .- -- (S A M).

when [space v] key pressed
set [Secret v] to [SAM]
broadcast (play letters v)

Works? Great, now delete the test script.

6Cat: the “make feedback” block

Click the Host (cat). Make a new block called make feedback with no inputs.

define make feedback
set [Feedback v] to []
set [i v] to (1)
repeat (3)
  if <(letter (i) of (Guess)) = (letter (i) of (Secret))> then
    set [Feedback v] to (join (Feedback) [✅])
  else
    set [Feedback v] to (join (Feedback) [❌])
  end
  change [i v] by (1)
end

It compares the guess and the secret letter by letter. Secret SAM, guess SAT → ✅✅❌.

7Cat: the game loop

The biggest script! It goes on the Host too. Take your time.

when green flag clicked
show list [Guesses v]
forever
  set [Secret v] to []
  repeat (3)
    set [Secret v] to (join (Secret) (item (pick random (1) to (length of [Letters v])) of [Letters v]))
  end
  set [Tries v] to (0)
  set [Replays v] to (0)
  set [Solved v] to (0)
  delete all of [Guesses v]
  say [Listen carefully...]
  wait (0.5) seconds
  broadcast (play letters v) and wait
  say []
  set [Question v] to [Which 3 letters did you hear?]
  repeat until <(Solved) = (1)>
    ask (Question) and wait
    set [Guess v] to (answer)
    if <(length of (Guess)) = (3)> then
      change [Tries v] by (1)
      make feedback :: custom
      add (join (Guess) (join [   ] (Feedback))) to [Guesses v]
      if <(Guess) = (Secret)> then
        set [Solved v] to (1)
      else
        set [Question v] to [Not yet! Check your guesses and try again.]
      end
    else
      set [Question v] to [Please type exactly 3 letters.]
    end
  end
  say (join [Correct! It was ] (join (Secret) (join [. Tries: ] (join (Tries) (join [, replays: ] (Replays)))))) for (4) seconds
  ask [Press Enter for a new round.] and wait
end

In the add … to Guesses block, the empty-looking box in the middle has 3 spaces typed in it, so the guess and the ✅❌ don't stick together.

The 3 parts of the loop

8The buttons

Replay Button

when this sprite clicked
if <(Playing) = (0)> then
  if <(Solved) = (0)> then
    change [Replays v] by (1)
  end
  broadcast (play letters v)
end

The Playing check stops the letters from playing twice at the same time if you click very fast.

Cheat Button

Make a new message called toggle cheat sheet.

when this sprite clicked
broadcast (toggle cheat sheet v)

Cheat Sheet

when green flag clicked
hide
set [showing v] to (0)

when I receive [toggle cheat sheet v]
if <(showing) = (0)> then
  show
  go to [front v] layer
  hide list [Guesses v]
  set [showing v] to (1)
else
  hide
  show list [Guesses v]
  set [showing v] to (0)
end

The cheat sheet sits in the same place as the Guesses list, so we hide the list while the sheet is showing.

9Play-test checklist

Click the green flag and try each of these. Tick them off as you go.

Something wrong?

Challenges 🚀

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