Scratch Game Academy

01

Lesson 1 · Sprites, Motion, Variables

Meet Your Shark 🦈

Stage setup · Arrow key movement · Score, Lives, Health variables · HUD display

🌊

▼

By the end of Lesson 1 you'll have an ocean scene, a shark that moves smoothly in all four directions, and a working HUD (heads-up display) showing Score, Lives, and Health on screen. You'll understand what variables are and why games need them.

Part 1 — Setting Up the Ocean

Open ScratchGo to scratch.mit.edu → Click Create. You'll see: the Stage (your game window, 480×360 pixels), the Sprite List, and the Code Blocks on the left.
Add your first backdrop — Shallow WaterClick the Stage thumbnail (bottom-right) → Choose a Backdrop → search "Underwater 1". This will be your Level 1 background. Later you'll add more backdrops for higher levels.
Delete the cat, add a SharkRight-click the cat → Delete. Click Choose a Sprite → search Shark. If you can't find one, use Paint to draw a simple shark shape. Resize it so it fits comfortably on the stage (try 80px wide).
Position the shark at the centre-leftDrag the shark to around x: -150, y: 0 on the stage. This will be its start position.

🧠 Key Concept: The Coordinate System

Scratch uses X and Y coordinates. The centre of the stage is (0, 0). X goes from -240 (left edge) to +240 (right edge). Y goes from -180 (bottom) to +180 (top). Every sprite has an X and Y position at all times.

Part 2 — Moving the Shark

Click on the Shark sprite — all code goes hereMake sure the shark is highlighted in the sprite list before dragging blocks.
Build the movement code:

🚩 when Green Flag clicked

go to x: (-150) y: (0)

forever

if <key [right arrow ▼] pressed?> then

change x by (6)

point in direction (90)

if <key [left arrow ▼] pressed?> then

change x by (-6)

point in direction (-90)

if <key [up arrow ▼] pressed?> then

change y by (5)

if <key [down arrow ▼] pressed?> then

change y by (-5)

Press the green flag and test it. The shark should move in all 4 directions.
Keep the shark inside the stageAdd this inside the forever loop to stop the shark going off-screen:

if on edge, bounce

Or for more control, use: if x position > 230 → set x to 230 (repeat for all 4 edges).

The forever loop runs 30 times per second. Each time it checks: "is a key being pressed?" This is called a polling loop — the same technique used in real game engines.

Part 3 — Creating All Your Variables

Now we'll create all the variables the game will need. Go to Variables → Make a Variable for each one. Set them all to "For all sprites".

Variable Name	Type	Starting Value	Purpose
Score	Number	0	Points earned by catching fish
HiScore	Number	0	Best score ever — survives between games
Lives	Number	3	Lives remaining — lose all = Game Over
Health	Number	100	Hit points — drains from hazards
Level	Number	1	Current level (1–6)
FishSpeed	Number	3	How fast fish move across the screen
TimeBonus	Number	30	Seconds left in the level — becomes bonus points
PoisonActive	Boolean	0	1 = shark is poisoned, 0 = shark is fine

Part 4 — The startGame Function (Preview)

Set all starting values when the green flag is clickedAdd these at the top of your shark's green flag script, above the forever loop:

set [Score ▼] to (0)

set [Lives ▼] to (3)

set [Health ▼] to (100)

set [Level ▼] to (1)

set [FishSpeed ▼] to (3)

set [TimeBonus ▼] to (30)

set [PoisonActive ▼] to (0)

In Lesson 3 we'll move all of this into a proper named function called startGame.

Part 5 — HUD: Showing Variables on Screen

Show Score, Lives and Health on screenTick the checkbox next to each variable in the Variables palette. They appear as monitors on the stage. Drag them to neat positions — Score top-left, Lives top-centre, Health top-right.
Hide FishSpeed, PoisonActive, Level from the playerUntick those checkboxes — the player doesn't need to see those. Or right-click a monitor and choose hide.

In a real game you'd build a custom health bar sprite. For now the variable monitor is fine — we'll polish it in Lesson 6.

🔥 Extension Challenge

Make the shark animate as it swims. In the Costumes tab, duplicate the shark costume and slightly move the tail fin. Then add next costume inside a wait 0.15 seconds loop running alongside your movement code.

✅ Lesson 1 Checklist

Ocean backdrop is displayed
Shark sprite moves with all 4 arrow keys
Shark stays within the stage edges
All 8 variables are created
Score, Lives and Health show on screen
All values reset correctly when green flag is clicked
You can explain: what a variable is, what a coordinate is, what a forever loop does

02

Lesson 2 · Clones, Loops & Conditionals

Release the Fish! 🐟

Clones · Random spawning · Collision detection · Multi-value fish

🐠

▼

By the end of Lesson 2 your game will have multiple types of fish spawning from the right side. Catching them adds to the score (different fish = different points). Missing them costs a life. A golden fish appears rarely for bonus points.

Part 1 — Add Three Fish Sprites

Add a regular fishClick Choose a Sprite → search Fish. Pick one and rename it "Fish" in the sprite info panel. Resize it to about 50px wide.
Add a second fish — the Bonus FishAdd another fish sprite. Rename it "GoldFish". Change its colour in the Costumes tab — select the fish shape and use the fill tool to make it golden/yellow. This fish will be worth 3 points.
Add a third fish — the Speed FishAdd a third fish sprite, rename it "FastFish". Make it a bright red/pink colour. This fish moves fast but is only worth 1 point.

🧠 Key Concept: Clones

A clone is a temporary copy of a sprite. The original sprite hides itself and acts as a factory — it produces clones over and over. Each clone runs its own code, moves independently, and can delete itself. This lets you have many fish on screen without needing many sprites.

Part 2 — Regular Fish Clone System

Green flag script — the factory

🚩 when Green Flag clicked

hide

forever

create clone of [myself ▼]

wait (pick random (1) to (3)) seconds
Clone startup script — each fish behaves on its own

when I start as a clone

show

go to x: (240) y: (pick random (-160) to (160))

set size to (pick random (60) to (100))%

forever

change x by ((0) - (FishSpeed))

if <touching [Shark ▼]?> then

change [Score ▼] by (1)

play sound [Pop ▼]

delete this clone

if <(x position) < (-240)> then

change [Lives ▼] by (-1)

delete this clone

Using pick random for both the Y position and size makes each fish feel unique. Varying size also adds an illusion of depth — bigger fish look closer.

Part 3 — Golden Fish (3 points, rare)

GoldFish spawns less often and is worth more

🚩 when Green Flag clicked

hide

forever

create clone of [myself ▼]

wait (pick random (5) to (10)) seconds

when I start as a clone

show

go to x: (240) y: (pick random (-150) to (150))

forever

change x by ((0) - (FishSpeed))

change y by (pick random (-2) to (2))

if <touching [Shark ▼]?> then

change [Score ▼] by (3)

play sound [Ding ▼]

delete this clone

if <(x position) < (-240)> then

delete this clone

Golden fish do NOT cost a life if missed — they're a bonus opportunity only. The wobbly Y movement makes them harder to catch.

Part 4 — Fast Fish (hard to catch, 1 point)

FastFish uses a local speed multiplier

🚩 when Green Flag clicked

hide

forever

create clone of [myself ▼]

wait (pick random (3) to (6)) seconds

when I start as a clone

show

go to x: (240) y: (pick random (-150) to (150))

forever

change x by ((0) - ((FishSpeed) * (2)))

if <touching [Shark ▼]?> then

change [Score ▼] by (1)

delete this clone

if <(x position) < (-240)> then

change [Lives ▼] by (-1)

delete this clone

Multiplying FishSpeed by 2 means FastFish always moves at double the current level speed — this scales automatically as difficulty increases.

Part 5 — Game Over Check

On the Shark sprite, monitor lives in the forever loop

if <(Lives) < (1)> then

broadcast [GameOver ▼]

stop [this script ▼]

We'll build the proper Game Over screen in Lesson 4. For now this just stops the shark moving.

HiScore: Add this check after updating Score — if Score > HiScore → set HiScore to Score. The HiScore variable never gets reset by startGame, so it persists between games in the same session.

🔥 Extension Challenges

Make GoldFish flash between two costumes using a next costume / wait 0.2s loop so it's easy to spot
Add a brief score popup: when a fish is caught, make a clone of a "score text" sprite that floats upward and fades out
Play a different sound for each fish type (Pop for regular, Ding for gold, Whoosh for fast)

✅ Lesson 2 Checklist

Regular fish spawn randomly from the right at varying heights and sizes
Golden fish appear less often, worth 3 points, and wobble as they swim
Fast fish move at double speed and are harder to catch
Catching any fish increases Score correctly
Missing a regular or fast fish costs 1 life
HiScore updates whenever Score beats the previous best
You can explain: what a clone is, what a Boolean condition is, what collision detection means

03

Lesson 3 · Custom Blocks (Functions)

Tidy Code with Functions 🧩

Define blocks · Parameters · Abstraction · DRY principle

⚙️

▼

By the end of Lesson 3 you'll have reorganised your entire game into clean, named custom blocks: startGame, catchFish(points), loseLife, damageShark(amount), spawnFish, and nextLevel. You'll understand why functions are one of the most important tools in programming.

🧠 What is a Function?

A function (called a Custom Block in Scratch) is a named chunk of code you can reuse. Instead of writing the same logic in ten places, you write it once, give it a name, and call that name whenever you need it.

The two big benefits: DRY (Don't Repeat Yourself — less code to write) and maintainability (if you want to change how catching a fish works, you change it in one place, not everywhere it happens).

Function 1 — startGame (Shark sprite)

Create the custom blockClick the Shark sprite → My Blocks → Make a Block → name it startGame → click OK.
Move all your setup code into it

define startGame

set [Score ▼] to (0)

set [Lives ▼] to (3)

set [Health ▼] to (100)

set [Level ▼] to (1)

set [FishSpeed ▼] to (3)

set [TimeBonus ▼] to (30)

set [PoisonActive ▼] to (0)

go to x: (-150) y: (0)

show

switch backdrop to [Underwater 1 ▼]
Call it from the green flag

🚩 when Green Flag clicked

startGame

forever

— (movement code) —

Function 2 — catchFish(points) with a Parameter

Create catchFish with an inputGo to My Blocks (on the Fish sprite) → Make a Block → name it catchFish. Click Add an input (number or text) and name it points. Click OK.
Build the block using the parameter

define catchFish (points)

change [Score ▼] by (points)

if <(Score) > (HiScore)> then

set [HiScore ▼] to (Score)

play sound [Pop ▼] until done

delete this clone
Call it differently for each fish type

catchFish (1)

← for regular fish

catchFish (3)

← for golden fish

catchFish (1)

← for fast fish

Same function, different arguments. The word inside the brackets is called an argument — the value you pass into the parameter.

Function 3 — loseLife (Fish sprite)

Create loseLife on the Fish sprite

define loseLife

change [Lives ▼] by (-1)

play sound [Oops ▼]

if <(Lives) < (1)> then

broadcast [GameOver ▼]

Function 4 — damageShark(amount) (Shark sprite)

This will be used by enemies in Lesson 4

define damageShark (amount)

if <(PoisonActive) = (0)> then

change [Health ▼] by ((0) - (amount))

set [color ▼] effect to (50)

wait (0.2) seconds

clear graphic effects

if <(Health) < (1)> then

change [Lives ▼] by (-1)

set [Health ▼] to (100)

if <(Lives) < (1)> then

broadcast [GameOver ▼]

When health hits zero, the shark loses a life but health resets to 100 — giving the player a chance to survive.

Function 5 — nextLevel (Shark sprite)

Increase difficulty and update the scene

define nextLevel

change [Level ▼] by (1)

change [FishSpeed ▼] by (1)

change [Score ▼] by (TimeBonus)

set [Health ▼] to (100)

set [TimeBonus ▼] to (30)

next backdrop

say (join [Level ] (Level)) for (2) secs

broadcast [LevelUp ▼]

Notice how nextLevel also adds the TimeBonus to Score and resets Health — the player is rewarded for completing a level quickly and starts fresh. This is a game design decision, not just a coding choice.

Calling nextLevel — Every 5 Fish Caught

Add this check to the shark's forever loop

if <((Score) mod (5)) = (0) and (Score) > (0)> then

nextLevel

mod (modulo) gives the remainder of division. 15 mod 5 = 0, 16 mod 5 = 1. So this fires at exactly 5, 10, 15, 20 fish caught.

🔥 Extension Challenge — Function with boolean parameter

Edit loseLife to accept a boolean parameter showWarning. If it's 1, show a red flash on screen. If it's 0, just deduct quietly. This teaches conditional logic inside functions.

✅ Lesson 3 Checklist

startGame resets all 8 variables and is called from the green flag
catchFish(points) uses a parameter and updates HiScore
loseLife deducts a life and broadcasts GameOver when Lives = 0
damageShark(amount) reduces Health and handles health = 0
nextLevel increases Level and FishSpeed, adds TimeBonus to Score, changes backdrop
The game still plays exactly as before — functions didn't change behaviour, just organisation
You can explain: what a parameter is, what DRY means, why functions help with debugging

04

Lesson 4 · Enemies, Health & Hazards

Danger in the Deep ☠️

Jellyfish · Mines · Pufferfish · Octopus · Health system · Poison effect

🪼

▼

By the end of Lesson 4 your shark will face five types of hazard: a jellyfish that drains health, a mine that causes instant life loss, a pufferfish that poisons the shark slowing it down, an octopus that blocks movement, and a whirlpool that briefly pulls the shark off course.

☠️ Enemies & Hazards Guide

🪼 Jellyfish

Floats up and down slowly. Appears from Level 1.

Effect: -10 Health per second of contact

💣 Mine

Drifts slowly across the screen. Appears from Level 2.

Effect: -1 Life instantly on touch

🐡 Pufferfish

Swims like a fish but inflates when touched. Level 3+.

Effect: Activates PoisonActive for 5 seconds — shark moves at half speed

🐙 Octopus

Emerges from the bottom. Tentacles grab the shark. Level 4+.

Effect: Freezes shark movement for 2 seconds, -15 Health

🌀 Whirlpool

Appears randomly on screen, slowly rotates. Level 5+.

Effect: Pushes shark in a random direction, -5 Health

Hazard 1 — Jellyfish

Add a Jellyfish spriteSearch the sprite library for "Jellyfish" or draw one. Rename it "Jellyfish". Make it semi-transparent in the costumes editor (set fill opacity to 70%).
Factory script (green flag)

🚩 when Green Flag clicked

hide

forever

create clone of [myself ▼]

wait (pick random (4) to (8)) seconds
Clone script — floating movement

when I start as a clone

show

go to x: (pick random (-200) to (200)) y: (-200)

forever

change y by (2)

change x by (pick random (-1) to (1))

if <touching [Shark ▼]?> then

damageShark (10)

wait (0.5) seconds

if <(y position) > (200)> then

delete this clone

The wait 0.5 seconds after dealing damage prevents the shark from losing all health instantly — it caps the damage rate to 20 HP per second.

Hazard 2 — Mine

Add a Mine spriteDraw a simple black circle with small spikes (like a sea mine) in the Paint editor, or search the library. Rename it "Mine".
Mine clone script

🚩 when Green Flag clicked

hide

forever

if <(Level) > (1)> then

create clone of [myself ▼]

wait (pick random (6) to (12)) seconds

when I start as a clone

show

go to x: (240) y: (pick random (-150) to (150))

forever

change x by (-1)

if <touching [Shark ▼]?> then

change [Lives ▼] by (-1)

set [ghost ▼] effect to (80)

wait (0.3) seconds

delete this clone

if <(x position) < (-250)> then

delete this clone

Mines only start appearing from Level 2 (the if Level > 1 check). They're slow but deadly — instant life loss.

Hazard 3 — Pufferfish (Poison)

Add a Pufferfish spriteSearch the library or paint a round fish. Give it two costumes: normal (small) and puffed up (large circle). Rename it "Pufferfish".
Poison effect script

when I start as a clone

show

switch costume to [puffer-normal ▼]

go to x: (240) y: (pick random (-150) to (150))

forever

change x by ((0) - (FishSpeed))

if <touching [Shark ▼]?> then

switch costume to [puffer-big ▼]

set [PoisonActive ▼] to (1)

wait (5) seconds

set [PoisonActive ▼] to (0)

delete this clone
Slow the shark when poisoned — modify movement code In the shark's movement forever loop, change the movement amounts:

if <key [right arrow ▼] pressed?> then

if <(PoisonActive) = (1)> then

change x by (3)

else

change x by (6)

Repeat this pattern for all 4 directions. When poisoned, the shark moves at half speed. The same pattern goes for Y movement.

Hazard 4 — Octopus (Freeze)

Add Octopus sprite from the libraryRename it "Octopus". It will rise from the bottom and broadcast a freeze event when touched.
Octopus clone + freeze broadcast

when I start as a clone

show

go to x: (pick random (-180) to (180)) y: (-200)

repeat (60)

change y by (3)

if <touching [Shark ▼]?> then

broadcast [FreezeShark ▼]

damageShark (15)

delete this clone

delete this clone

when I receive [FreezeShark ▼]
← Add this to the SHARK sprite
stop [other scripts in sprite ▼]

set [color ▼] effect to (150)

wait (2) seconds

clear graphic effects

broadcast [UnfreezeShark ▼]

Using broadcast to communicate between sprites is a key Scratch technique. It's a simplified version of the event-driven programming pattern used in real apps and games.

Hazard 5 — Whirlpool

Create a Whirlpool sprite in the Paint editorDraw a blue spiral. Give it two costumes and animate it. Rename it "Whirlpool".
Whirlpool script — push effect

when I start as a clone

show

go to x: (pick random (-180) to (180)) y: (pick random (-150) to (150))

repeat (200)

next costume

wait (0.1) seconds

if <touching [Shark ▼]?> then

change x by (pick random (-20) to (20))

change y by (pick random (-20) to (20))

damageShark (5)

delete this clone

🔥 Extension Challenges

Add a visual health bar sprite: a long rectangle that changes width based on the Health variable using set size to (Health) % (width only)
Make the shark turn green and flash when PoisonActive = 1 using a colour effect loop
Add a power-up fish (a starfish?) — catching it sets Health back to 100 and gives 5 seconds of invincibility where damageShark does nothing

✅ Lesson 4 Checklist

Jellyfish drains Health by 10 on contact (with 0.5s cooldown)
Mines appear from Level 2 and instantly cost a life on contact
Pufferfish sets PoisonActive = 1 for 5 seconds, halving shark speed
Octopus broadcasts FreezeShark, stopping movement for 2 seconds
Whirlpool pushes the shark in a random direction
damageShark(amount) function is used by all enemies
Health dropping to 0 costs a life and resets Health to 100
You can explain: event-driven programming, what a broadcast does, why the damage cooldown is important

05

Lesson 5 · Levels & Changing Worlds

Level Up! 🌊

6 backdrops · Level transitions · Difficulty scaling · Game Over screen

⚡

▼

By the end of Lesson 5 your game will have 6 full levels, each with a different ocean backdrop, increasing difficulty, new enemies unlocking at specific levels, a TimeBonus countdown, and a polished Game Over screen that shows the final score and HiScore.

Part 1 — The 6 Level Backdrops

Go to the Stage → Backdrops tab. Add 6 backdrops in order. The next backdrop block in your nextLevel function will cycle through them automatically.

🌅

Level 1

Shallow Reef

Bright, colourful coral. "Underwater 1" from library.

🌿

Level 2

Seagrass Meadow

Murky green. "Underwater 2" from library.

🔆

Level 3

Open Ocean

Deep blue, less coral. Use "Blue Sky 2" recoloured.

🌑

Level 4

Twilight Zone

Dark purple. Use Paint — dark gradient background.

🔴

Level 5

Volcanic Vent

Dark red/orange glow. Paint a dark bg with orange spots.

🌌

Level 6

The Abyss

Near-black. Paint nearly black — adds dramatic tension.

After adding all 6 backdrops, check they appear in the right order in the Backdrops tab. next backdrop moves through them in order, looping back to the first if it reaches the end.

Part 2 — Level Difficulty Table

Your nextLevel function increases FishSpeed by 1 each time. Here's how each level feels:

Level	FishSpeed	Spawn Delay	New Enemies Unlocked	TimeBonus
1	3	1–3 sec	Jellyfish only	30
2	4	0.8–2.5 sec	Mines appear	30
3	5	0.6–2 sec	Pufferfish appear	30
4	6	0.5–1.5 sec	Octopus appears	30
5	7	0.4–1.2 sec	Whirlpools appear	30
6	8	0.3–1 sec	All enemies — survival mode	30

Part 3 — Level-Gated Enemy Spawning

Each enemy checks the Level variable before spawning You already did this for Mines. Do the same for each other enemy. Example — Pufferfish:

🚩 when Green Flag clicked

hide

forever

if <(Level) ≥ (3)> then

create clone of [myself ▼]

wait (pick random (5) to (10)) seconds

Apply this pattern to each enemy with their unlock level from the table above.

Part 4 — TimeBonus Countdown

Add a separate countdown script on the Shark

when I receive [LevelUp ▼]

repeat (30)

wait (1) seconds

if <(TimeBonus) > (0)> then

change [TimeBonus ▼] by (-1)

When a level starts (triggered by the LevelUp broadcast), TimeBonus counts down from 30 to 0. Whatever's left gets added to Score when nextLevel fires.

Part 5 — Winning at Level 6

Check if Level goes past 6 → trigger Win state Add to the nextLevel check in the forever loop:

if <(Level) > (6)> then

broadcast [YouWin ▼]

stop [this script ▼]

Part 6 — Game Over & You Win Screens

Create a "GameOver" spriteUse the Paint editor. Draw a dark rectangle that covers most of the stage. Add text: "GAME OVER", and use join blocks to show the score and HiScore. Add a "Press Space to Restart" instruction.
GameOver sprite code

🚩 when Green Flag clicked

hide

when I receive [GameOver ▼]

show

go to front layer

say (join [Score: ] (join (Score) (join [ Best: ] (HiScore))))

wait until <key [space ▼] pressed?>

hide

broadcast [RestartGame ▼]
Restart the game from broadcast On the Shark sprite, add:

when I receive [RestartGame ▼]

startGame

forever

— (movement code) —

Now the game fully restarts without needing to press the green flag again.
Create a YouWin screen similarlyDuplicate the GameOver sprite, change the text to "YOU WIN! 🏆", add a congratulations message with the final score, and trigger it from the YouWin broadcast.

🔥 Extension Challenges

Add a level transition animation — when LevelUp broadcasts, show a full-screen flash or a "LEVEL 2" text sprite that fades in and out before gameplay resumes
Play different background music per level using a music sprite that changes its costume/sound on each LevelUp broadcast
Add a combo multiplier — catch 3 fish in a row within 3 seconds, get 2x points. Miss one = combo resets

✅ Lesson 5 Checklist

All 6 backdrops are added to the Stage in order
Backdrop changes automatically with each level via next backdrop
Each enemy has a level gate — enemies unlock progressively
TimeBonus counts down during each level and is added to Score on level completion
Level 7 triggers a YouWin broadcast instead of a new level
Game Over screen shows Score and HiScore
Pressing Space on the Game Over screen fully restarts the game
You can explain: what event-driven programming is, how broadcasts enable sprite communication

06

Lesson 6 · Polish, Debug & Showcase

Make It Shine ✨

Sound · Health bar · Start screen · Debugging · Peer review · Share

🏆

▼

By the end of Lesson 6 your game will feel like a complete, polished product — with a start screen, background music that changes per level, a visual health bar, particle effects, and your project shared on the Scratch community.

Part 1 — Start Screen

Create a StartScreen spritePaint a large rectangle that covers the stage. Add your game title "SHARK ATTACK!", the controls (arrow keys to move, avoid enemies, catch fish), and "Press SPACE to Start".
StartScreen code

🚩 when Green Flag clicked

show

go to front layer

switch backdrop to [title-screen ▼]

wait until <key [space ▼] pressed?>

hide

broadcast [StartGame ▼]
Update all sprites to wait for StartGameChange every sprite's green flag script so their factories don't start until they receive the StartGame broadcast. This stops fish and enemies spawning before the player is ready.

Part 2 — Visual Health Bar

Create a HealthBar spriteIn the Paint editor, draw a green rectangle about 100px wide and 12px tall. Position it in the top-right corner of the stage.
Make it scale with Health

🚩 when Green Flag clicked

forever

set size to (Health) %

if <(Health) > (60)> then

set [color ▼] effect to (0)

else if <(Health) > (30)> then

set [color ▼] effect to (25)

else

set [color ▼] effect to (0) ... and make it flash red

Green = healthy (60–100), yellow = caution (30–60), red and flashing = danger (0–30). This gives the player at-a-glance health feedback.

Part 3 — Sound Design

Background musicAdd a Music sprite. On StartGame broadcast: play a looping background track. On LevelUp: switch to a slightly faster/more intense track. On GameOver: play a sad jingle.
Sound effects checklist
- 🎵 Regular fish caught: Pop
- 🎵 Gold fish caught: Ding / Tada
- 🎵 Life lost: Oops / Boing
- 🎵 Jellyfish hit: Zap / Crackle
- 🎵 Mine explodes: Boom / Crash
- 🎵 Poisoned: Wah Wah / Sad Trombone
- 🎵 Level up: Trumpet / Fanfare
- 🎵 Game over: Lose / Game Over
- 🎵 You win: Win / Cheer

Part 4 — Particle Effects

Create a "Particle" sprite — small sparkle/bubbleDraw a tiny star or circle in the Paint editor. This will be used for a catch effect.
Spawn particles when a fish is caught In your catchFish function, add before deleting the clone:

repeat (5)

create clone of [Particle ▼]

Then on the Particle sprite, when starting as a clone: go to the fish's position, move in a random direction, fade out (ghost effect 0→100), then delete.

Part 5 — Debugging Your Game

Playtest 3 full gamesWrite down: anything that crashes, any score that seems wrong, any enemy that behaves unexpectedly, anything that feels unfair or boring.
Use variable monitors to debugTick the checkbox on PoisonActive and Lives temporarily. Watch them change in real-time during play. Untick when fixed.
Give your game to someone else to play — don't explain anythingWatch where they get confused. If they can't figure out the controls, you need a better start screen. If they die without knowing why, your feedback needs improving.

Common bugs: score increasing multiple times per catch (fix: delete clone immediately after catchFish), enemies dealing damage too fast (fix: add a wait after damageShark), Level variable going past 6 (fix: cap with if Level > 6 → set Level to 6 OR trigger YouWin).

Part 6 — Share & Showcase

Write a project descriptionIn Scratch, click Share then fill in: Title ("SHARK ATTACK! by [Your Name]"), Instructions (arrow keys, what to avoid, how to score), and Notes (how long it took, what you're most proud of).
Peer reviewPlay two classmates' games. Leave a comment with: one specific thing you liked (be precise — not "it's good", but "the golden fish wobbling is a great challenge") and one constructive suggestion.

🌟 Bonus Mega-Challenges

If you finished everything — try these!

Power-up Starfish — catching it gives 10 seconds of invincibility (PoisonActive blocks damage already, use a similar InvincibleActive variable)
Scrolling seabed — create a long backdrop sprite and scroll it left at FishSpeed to give the illusion of movement
High score leaderboard — use Scratch's cloud variables (requires account) to store top 3 scores that persist between sessions for all players
Two-player mode — second shark controlled by WASD keys, competing for the same fish, each with their own score variable
Boss level at Level 6 — a giant whale that slowly moves across the screen. Takes 5 hits to kill (using a BossHealth variable). Defeating it gives 20 bonus points.

✅ Final Game Checklist — Is It Complete?

Start screen appears before gameplay begins
Shark moves in 4 directions, stays on stage
3 fish types: regular (1pt), golden (3pt, rare), fast (1pt, moves fast)
5 hazards: jellyfish (health drain), mine (instant life), pufferfish (poison/slow), octopus (freeze), whirlpool (push)
8 variables working: Score, HiScore, Lives, Health, Level, FishSpeed, TimeBonus, PoisonActive
6 custom functions: startGame, catchFish(points), loseLife, damageShark(amount), nextLevel, spawnFish
6 level backdrops change automatically
Enemies unlock progressively by level
TimeBonus countdown adds to Score each level
Visual health bar changes colour with health
Game Over screen shows Score + HiScore, restarts on Space
You Win screen appears after Level 6
Sound effects for every major event
Project shared on Scratch with title, instructions and description
You left constructive feedback on two classmates' games

🏆

You Did It!

You've built a complete game with 8 variables, 6 custom functions with parameters, 5 types of enemy, 6 changing levels, collision detection, health systems, event-driven programming and a polished UI. That's genuinely impressive — and it's the same set of ideas used in every game ever made.