Complete the core mechanic

Worked example

An input-to-feedback chain might be movement, pickup overlap, collected signal, manager score increment, then label refresh. Each stage has one clear responsibility. Scaffold C-BODY — Reusable top-down player with collision Setup: Create CharacterBody2D root Player at (80,180); add CollisionShape2D with CircleShape2D radius 14. Attach this script to Player and save Player.tscn. Use C-FREE-MOVE input actions. Root collision layer 1, mask 2. Create a separate StaticBody2D Wall on layer 2 mask 1 with RectangleShape2D collision and a Polygon2D rectangle as visible child. Instance both under an unscaled Node2D World. Do not put a body inside another physics body. ```gdscript extends CharacterBody2D @export var speed: float = 160.0 func _draw() -> void: draw_circle(Vector2.ZERO, 14.0, Color.CORNFLOWER_BLUE) draw_line(Vector2(-8, 0), Vector2(8, 0), Color.WHITE, 3.0) func _physics_process(_delta: float) -> void: velocity = Input.get_vector("move_left", "move_right", "move_up", "move_down") * speed move_and_slide() ``` Scaffold C-PLATFORM — A gravity-and-jump platform player Setup: CharacterBody2D root Player, child CollisionShape2D RectangleShape2D size (24,32), no scale changes. Layer 1 mask 2. StaticBody2D floor layer 2 mask 1 with rectangular collider. Add Input Map move_left, move_right and jump bound to Space. Place player above floor, not intersecting it. Coordinates use positive y downward. Attach script to Player. ```gdscript extends CharacterBody2D @export var speed: float = 160.0 @export var gravity: float = 900.0 @export var jump_speed: float = 340.0 func _draw() -> void: draw_rect(Rect2(-12, -16, 24, 32), Color.SKY_BLUE) draw_line(Vector2(-8, -4), Vector2(8, -4), Color.BLACK, 2.0) func _physics_process(delta: float) -> void: velocity.x = Input.get_axis("move_left", "move_right") * speed if not is_on_floor(): velocity.y += gravity * delta if Input.is_action_just_pressed("jump") and is_on_floor(): velocity.y = -jump_speed move_and_slide() ``` Scaffold C-DIALOGUE — Data-driven branching dialogue without personal data Setup: Create Control root Dialogue with VBoxContainer Box containing Label Line and Buttons A and B. Set Box anchors to full rect; Line autowrap if needed. Attach script to Dialogue. Data keys are fictional scene IDs. All three screens can fit in 640x360. This is a self-contained example; replace story text in the assignment. ```gdscript extends Control var page: String = "start" var story: Dictionary = { "start": {"text": "Two paths enter the archive.", "choices": [["Ask the keeper", "keeper"], ["Read a sign", "sign"]]}, "keeper": {"text": "The keeper offers a map.", "choices": [["Return", "start"]]}, "sign": {"text": "Quiet room to the east.", "choices": [["Return", "start"]]} } func _ready() -> void: $Box/A.pressed.connect(_choose.bind(0)) $Box/B.pressed.connect(_choose.bind(1)) _show() func _show() -> void: var entry: Dictionary = story[page] $Box/Line.text = entry["text"] var buttons: Array[Button] = [$Box/A, $Box/B] for i in range(buttons.size()): buttons[i].visible = i < entry["choices"].size() if buttons[i].visible: buttons[i].text = entry["choices"][i][0] $Box/A.grab_focus() func _choose(index: int) -> void: var choices: Array = story[page]["choices"] if index < 0 or index >= choices.size(): return page = str(choices[index][1]) _show() ```

Reusable top-down player with collision

GDScript (Godot 4, not Scratch, Python, JavaScript or C#). Scaffold C-BODY. Copy starts from this text. The desk does not run it.

Scene and node setup

Create CharacterBody2D root Player at (80,180); add CollisionShape2D with CircleShape2D radius 14. Attach this script to Player and save Player.tscn. Use C-FREE-MOVE input actions. Root collision layer 1, mask 2. Create a separate StaticBody2D Wall on layer 2 mask 1 with RectangleShape2D collision and a Polygon2D rectangle as visible child. Instance both under an unscaled Node2D World. Do not put a body inside another physics body.

extends CharacterBody2D
@export var speed: float = 160.0
func _draw() -> void:
    draw_circle(Vector2.ZERO, 14.0, Color.CORNFLOWER_BLUE)
    draw_line(Vector2(-8, 0), Vector2(8, 0), Color.WHITE, 3.0)
func _physics_process(_delta: float) -> void:
    velocity = Input.get_vector("move_left", "move_right", "move_up", "move_down") * speed
    move_and_slide()

Checks to run in the editor

• Player stops at the wall rather than passing through.
• Diagonal speed matches horizontal speed.
• Do not multiply velocity by delta before move_and_slide.

Native Godot 4.7.2.stable.official.ed1daf0bf headless compile and representative node-tree/runtime tests passed; see native-qa-results.json. Visual UI, audible output, exports and website submission still need separate checks.

A gravity-and-jump platform player

GDScript (Godot 4, not Scratch, Python, JavaScript or C#). Scaffold C-PLATFORM. Copy starts from this text. The desk does not run it.

Scene and node setup

CharacterBody2D root Player, child CollisionShape2D RectangleShape2D size (24,32), no scale changes. Layer 1 mask 2. StaticBody2D floor layer 2 mask 1 with rectangular collider. Add Input Map move_left, move_right and jump bound to Space. Place player above floor, not intersecting it. Coordinates use positive y downward. Attach script to Player.

extends CharacterBody2D
@export var speed: float = 160.0
@export var gravity: float = 900.0
@export var jump_speed: float = 340.0
func _draw() -> void:
    draw_rect(Rect2(-12, -16, 24, 32), Color.SKY_BLUE)
    draw_line(Vector2(-8, -4), Vector2(8, -4), Color.BLACK, 2.0)
func _physics_process(delta: float) -> void:
    velocity.x = Input.get_axis("move_left", "move_right") * speed
    if not is_on_floor():
        velocity.y += gravity * delta
    if Input.is_action_just_pressed("jump") and is_on_floor():
        velocity.y = -jump_speed
    move_and_slide()

Checks to run in the editor

• Player lands without sinking.
• Holding jump does not repeatedly jump in air.
• Do not multiply the whole velocity by delta before move_and_slide.

Native Godot 4.7.2.stable.official.ed1daf0bf headless compile and representative node-tree/runtime tests passed; see native-qa-results.json. Visual UI, audible output, exports and website submission still need separate checks.

Data-driven branching dialogue without personal data

GDScript (Godot 4, not Scratch, Python, JavaScript or C#). Scaffold C-DIALOGUE. Copy starts from this text. The desk does not run it.

Scene and node setup

Create Control root Dialogue with VBoxContainer Box containing Label Line and Buttons A and B. Set Box anchors to full rect; Line autowrap if needed. Attach script to Dialogue. Data keys are fictional scene IDs. All three screens can fit in 640x360. This is a self-contained example; replace story text in the assignment.

extends Control
var page: String = "start"
var story: Dictionary = {
    "start": {"text": "Two paths enter the archive.", "choices": [["Ask the keeper", "keeper"], ["Read a sign", "sign"]]},
    "keeper": {"text": "The keeper offers a map.", "choices": [["Return", "start"]]},
    "sign": {"text": "Quiet room to the east.", "choices": [["Return", "start"]]}
}
func _ready() -> void:
    $Box/A.pressed.connect(_choose.bind(0))
    $Box/B.pressed.connect(_choose.bind(1))
    _show()
func _show() -> void:
    var entry: Dictionary = story[page]
    $Box/Line.text = entry["text"]
    var buttons: Array[Button] = [$Box/A, $Box/B]
    for i in range(buttons.size()):
        buttons[i].visible = i < entry["choices"].size()
        if buttons[i].visible:
            buttons[i].text = entry["choices"][i][0]
    $Box/A.grab_focus()
func _choose(index: int) -> void:
    var choices: Array = story[page]["choices"]
    if index < 0 or index >= choices.size():
        return
    page = str(choices[index][1])
    _show()

Checks to run in the editor

• Both start choices work.
• Return works from each branch; hidden B cannot trigger a nonexistent choice.

Native Godot 4.7.2.stable.official.ed1daf0bf headless compile and representative node-tree/runtime tests passed; see native-qa-results.json. Visual UI, audible output, exports and website submission still need separate checks.

Complete the core mechanic — evidence task

1. 1. Finish the core action and test three ordinary cases.
2. 2. Annotate reused versus newly written code.

Deliverable. Core-mechanic checkpoint and three-case log.

Acceptance checks

• VGC-L081-T1. All three cases produce the intended state change.
• VGC-L081-T2. Gameplay does not require Remote Inspector edits.

Understanding question. Why identify reused code rather than claiming everything is new?

Include a downloadable project ZIP with project.godot, .tscn, .gd and original asset files when code changes. A private, teacher-accessible download link to that ZIP is equivalent. Screenshots or a playthrough do not replace editable source.

If this is still shaky. Use your state-owner diagram to fix one system at a time. Keep the vertical-slice checkpoint available for comparison. Start with the first assigned task and re-run its acceptance test before adding the remaining feature.

Optional extra. Add one optional challenge only after the complete minimum loop passes. Document one changed parameter, your prediction, and the observed effect; optional, not required for completion.

Turn in typed notes and a JPEG, PNG, or WebP screenshot. One https address is stored as text and is not opened, extracted, or run. An MP3, WAV, M4A, MP4, or WebM file up to 4 MB can show a demo. The demo does not replace editable source. Zip and code files are refused. If there is no private link, keep the project on the family computer and review the code in person.

• Your first 2D game

  Free public tutorial; no account; external asset download is optional, not used by this course.

  · Opening this link does not submit the lesson.