A feature-rich Flappy Bird clone built with WPF (.NET) using a clean 3-layer architecture. Developed as a group project for the PRN212 course.

Features

• Classic Flappy Bird gameplay -- tap Space to flap, avoid pipes and obstacles
• Dynamic difficulty scaling -- speed increases, animated pipes appear, and new obstacle types spawn as your score climbs
• Day/Night cycle -- smooth theme transitions triggered by in-game gates or the N key
• 3 bird skins -- Yellow (Classic), Green, and Purple, each with unique fly/fall sprites for both themes
• Animated pipes -- oscillating, target-movement, and jump-pattern animations that intensify with score
• Group pipes (Staircase) -- clusters of 2-4 pipes arranged in ascending/descending staircase formations
• NoTouch obstacles -- bouncing hazards that spawn in increasing numbers after 10 pipes
• Gates -- collectible portals that toggle the day/night theme
• Persistent high score -- saved locally to file
• Background music and sound effects -- BGM with looping, jump/point/fail SFX
• Video background -- animated login screen with looping MP4
• Configurable pipe speed -- adjustable from 3 to 10 via Settings

Architecture

The project follows a 3-layer architecture with clear separation of concerns:

FlappyBirdGame.sln
|
+-- PRN212.G5.FlappyBird/        # Presentation Layer (WPF)
|   +-- LoginWindow.xaml/.cs      # Login screen + BGM + video background
|   +-- MainWindow.xaml/.cs       # Core game window & game loop
|   +-- SelectSkin.xaml/.cs       # Bird skin selection UI
|   +-- Views/
|   |   +-- SettingsWindow.xaml/.cs  # Speed & volume settings
|   +-- Helpers/
|   |   +-- AnimationHelper.cs    # Day/night transitions, death animation
|   |   +-- AssetHelper.cs        # Asset path & bitmap loading utilities
|   |   +-- BirdFrameManager.cs   # Bird sprite frame management per skin/theme
|   |   +-- GameUIRenderer.cs     # Creates & updates pipe/cloud/obstacle UI elements
|   |   +-- SoundHelper.cs        # Sound effect playback
|   +-- Assets/                   # Images, audio, video resources
|
+-- FlappyBird.Business/          # Business Logic Layer
|   +-- Models/
|   |   +-- BirdState.cs          # Bird position, speed, rotation, animation state
|   |   +-- CloudState.cs         # Cloud position and size
|   |   +-- GateState.cs          # Gate position and activation status
|   |   +-- NoTouchState.cs       # NoTouch obstacle position and oscillation
|   |   +-- PipePairState.cs      # Pipe pair geometry, animation, and group info
|   +-- Services/
|       +-- BirdService.cs        # Bird physics (gravity, jump, rotation)
|       +-- GameService.cs        # Score, high score, game state, grace period
|       +-- StageService.cs       # Pipe generation, difficulty scaling, obstacles
|
+-- FlappyBird.Data/              # Data Access Layer
    +-- Repositories/
        +-- GameRepo.cs           # High score file persistence

How It Works

Game Loop (20ms tick)

1. Bird physics -- gravity pulls the bird down each frame; Space key applies upward force
2. Pipe movement -- all pipes scroll left at baseSpeed + score * 0.1
3. Pipe recycling -- when a pipe exits the left edge, it is repositioned to the right with new random properties
4. Collision detection -- AABB (Axis-Aligned Bounding Box) checks against pipes, obstacles, ground, and ceiling
5. Score -- incremented each time a pipe is recycled past the bird

Difficulty Progression

Score	Pipe Animation	Oscillation	Jump Pattern	Group Pipes	NoTouch
0-9	None	-	-	-	-
10-14	50% chance	50%	-	-	Phase spawning
15-19	50% chance	50%	-	45% chance	Phase spawning
20-29	65% chance	65%	30%	45% chance	Phase spawning
30-39	80% chance	80%	30%	45% chance	Phase spawning
40+	80% chance	80%	30%	65% chance	Phase spawning

Key Constants

Parameter	Value
Canvas Height	500px
Pipe Width	80px
Gap between pipes	180px
Pipe Spacing	260px
Group Pipe Spacing	90px
Gravity	1.0 per frame
Jump Strength	-10.0
Grace Period	60 frames

Getting Started

Prerequisites

• .NET 6.0+ SDK (https://dotnet.microsoft.com/download)
• Windows OS (WPF requirement)

Run the Game

# Clone the repository
git clone <repo-url>
cd FlappyBird

# Build and run
dotnet run --project PRN212.G5.FlappyBird

Controls

Key	Action
Space	Flap / Jump
N	Toggle Day/Night
Replay Button	Restart after Game Over
Back Button	Return to Login screen

Assets

File	Purpose
birdfly-1/2/3.png	Bird fly sprites (3 skins)
birdfall-1/2/3.png	Bird fall sprites (3 skins)
Pipe-day/night.png	Pipe sprites for each theme
DayStage/NightStage.jpg	Background images
DayGround/NightGround.jpg	Ground images
Cloud-Day/Night.png	Cloud sprites
NoTouch.png	NoTouch obstacle sprite
BGM.mp3	Background music
Jump/Point/Fail.mp3	Sound effects
LoginWindowBG.mp4	Login screen video background