godot-genre-platformer

What this skill does

# Genre: Platformer

Expert blueprint for platformers emphasizing movement feel, level design, and player satisfaction.

## NEVER Do (Expert Anti-Patterns)

### Physics & Movement Feel
- NEVER multiply velocity by `delta` before `move_and_slide()`; the method internalizes the timestep.
- NEVER skip **Coyote Time** (approx 0.1s); without this grace period, jumps will feel unresponsive when walking off ledges.
- NEVER ignore **Jump Buffering** (approx 0.15s); players expect to jump the instant they touch the ground if they pressed the button early.
- NEVER use a fixed jump height; strictly implement **Variable Jump Height** (cut velocity on release) for player expression.
- NEVER forget to scale gravity by `delta` before adding to velocity; gravity is an acceleration and must be frame-rate independent.
- NEVER rely on discrete collision for high-speed movement; strictly use `CCD_MODE_CAST_RAY` to prevent tunneling through geometry.
- NEVER use `move_and_collide()` for standard traversal; it lacks the slope/stair handling of `move_and_slide()`.
- NEVER check coyote or buffer timers using exact equality (== 0.0); strictly use `is_equal_approx()` or `>= 0.0`.

### Polish & Level Design
- NEVER use linear camera snapping; strictly use **Camera Smoothing** or `lerp()` to prevent motion sickness.
- NEVER skip **Squash and Stretch** on jump/land; movement feels weightless without these subtle visual "juice" cues.
- NEVER create **Blind Jumps**; strictly use camera look-ahead or zoom triggers to reveal landing zones.
- NEVER use individual `Sprite2D` nodes for level geometry; strictly use **TileMapLayer** for optimized collision and rendering.
- NEVER use complex/concave `CollisionShape2D` for the player; strictly favor primitive shapes (Capsule/Rectangle) for stability.

### Architecture & Performance
- NEVER use `CharacterBody2D` for simple moving platforms; strictly use **AnimatableBody2D** and enable `sync_to_physics`.
- NEVER ignore `platform_on_leave` for descending platforms; use `PLATFORM_ON_LEAVE_ADD_UPWARD_VELOCITY` to preserve jump impulse.
- NEVER disable `recovery_as_collision` on the player character; it is required for correct floor snapping reports.
- NEVER use the `!` (NOT) operator in AnimationTree expressions; strictly use `is_walking == false`.
- NEVER use standard Strings for high-frequency state checks; strictly use `StringName` (e.g., `&"jumping"`).
- NEVER load heavy level chunks synchronously; strictly use `ResourceLoader.load_threaded_request()` to prevent frame stutters.

---

## 🛠 Expert Components (scripts/)

### Original Expert Patterns
- [advanced_platformer_controller.gd](scripts/advanced_platformer_controller.gd) - Professional-grade `CharacterBody2D` controller with Coyote Time, Jump Buffering, and variable height.

### Modular Components
- [coyote_timer.gd](scripts/coyote_timer.gd) - Grace period logic for jumps after leaving a floor's edge.
- [jump_buffer.gd](scripts/jump_buffer.gd) - Input queuing system for ultra-responsive landing jumps.
- [player_ground_controller.gd](scripts/player_ground_controller.gd) - Advanced movement with floor constant speed and slope-aware snapping.
- [variable_jump.gd](scripts/variable_jump.gd) - Scalable jump height using velocity cutoff on button release.
- [wall_slide_sensor.gd](scripts/wall_slide_sensor.gd) - Nodeless wall detection using high-performance physics raycasts.
- [ledge_grab_sensor.gd](scripts/ledge_grab_sensor.gd) - PhysicsShapeQuery-based ledge detection without Area2D nodes.
- [custom_collision_slider.gd](scripts/custom_collision_slider.gd) - Manual sliding response for high-speed inter-frame precision.
- [synchronized_platform.gd](scripts/synchronized_platform.gd) - `AnimatableBody2D` config for physics-synced movement.
- [fast_projectile_ccd.gd](scripts/fast_projectile_ccd.gd) - Continuous Collision Detection setup to prevent tunneling.
- [platformer_animation_sync.gd](scripts/platformer_animation_sync.gd) - Boolean-safe sync between physics states and AnimationTree.
- [platformer_camera.gd](scripts/platformer_camera.gd) - Camera smoothing and look-ahead logic for platforming focus.

---

## Core Loop

`Jump → Navigate Obstacles → Reach Goal → Next Level`

## Skill Chain

`godot-project-foundations`, `godot-characterbody-2d`, `godot-input-handling`, `animation`, `sound-manager`, `tilemap-setup`, `camera-2d`

---

## Movement Feel ("Game Feel")

The most critical aspect of platformers. Players should feel **precise, responsive, and in control**.

### Input Responsiveness

```gdscript
# Instant direction changes - no acceleration on ground
func _physics_process(delta: float) -> void:
    var input_dir := Input.get_axis("move_left", "move_right")
    
    # Ground movement: instant response
    if is_on_floor():
        velocity.x = input_dir * MOVE_SPEED
    else:
        # Air movement: slightly reduced control
        velocity.x = move_toward(velocity.x, input_dir * MOVE_SPEED, AIR_ACCEL * delta)
```

### Coyote Time (Grace Period)

Allow jumping briefly after leaving a platform:

```gdscript
var coyote_timer: float = 0.0
const COYOTE_TIME := 0.1  # 100ms grace period

func _physics_process(delta: float) -> void:
    if is_on_floor():
        coyote_timer = COYOTE_TIME
    else:
        coyote_timer = max(0, coyote_timer - delta)
    
    # Can jump if on floor OR within coyote time
    if Input.is_action_just_pressed("jump") and coyote_timer > 0:
        velocity.y = JUMP_VELOCITY
        coyote_timer = 0
```

### Jump Buffering

Register jumps pressed slightly before landing:

```gdscript
var jump_buffer: float = 0.0
const JUMP_BUFFER_TIME := 0.15

func _physics_process(delta: float) -> void:
    if Input.is_action_just_pressed("jump"):
        jump_buffer = JUMP_BUFFER_TIME
    else:
        jump_buffer = max(0, jump_buffer - delta)
    
    if is_on_floor() and jump_buffer > 0:
        velocity.y = JUMP_VELOCITY
        jump_buffer = 0
```

### Variable Jump Height

```gdscript
const JUMP_VELOCITY := -400.0
const JUMP_RELEASE_MULTIPLIER := 0.5

func _physics_process(delta: float) -> void:
    # Cut jump short when button released
    if Input.is_action_just_released("jump") and velocity.y < 0:
        velocity.y *= JUMP_RELEASE_MULTIPLIER
```

### Gravity Tuning

```gdscript
const GRAVITY := 980.0
const FALL_GRAVITY_MULTIPLIER := 1.5  # Faster falls feel better
const MAX_FALL_SPEED := 600.0

func apply_gravity(delta: float) -> void:
    var grav := GRAVITY
    if velocity.y > 0:  # Falling
        grav *= FALL_GRAVITY_MULTIPLIER
    velocity.y = min(velocity.y + grav * delta, MAX_FALL_SPEED)
```

---

## Level Design Principles

### The "Teaching Trilogy"

1. **Introduction**: Safe environment to learn mechanic
2. **Challenge**: Apply mechanic with moderate risk
3. **Twist**: Combine with other mechanics or time pressure

### Visual Language

- **Safe platforms**: Distinct color/texture
- **Hazards**: Red/orange tints, spikes, glow effects
- **Collectibles**: Bright, animated, particle effects
- **Secrets**: Subtle environmental hints

### Flow and Pacing

```
Easy → Easy → Medium → CHECKPOINT → Medium → Hard → CHECKPOINT → Boss
```

### Camera Design

```gdscript
# Look-ahead camera for platformers
extends Camera2D

@export var look_ahead_distance := 100.0
@export var look_ahead_speed := 3.0

var target_offset := Vector2.ZERO

func _process(delta: float) -> void:
    var player_velocity: Vector2 = target.velocity
    var desired_offset := player_velocity.normalized() * look_ahead_distance
    target_offset = target_offset.lerp(desired_offset, look_ahead_speed * delta)
    offset = target_offset
```

---

## Platformer Sub-Genres

### Precision Platformers (Celeste, Super Meat Boy)

- Instant respawn on death
- Very tight controls (no acceleration)
- Checkpoints every few seconds of gameplay
- Death is learning, not punishment

### Collectathon (Mario 64, Banjo-Kazooie)

- Large hub worlds with objectives
- Multiple abilities unlocked over time
- Backtracking encour