🎮 Space Invaders — OOP C++ Game

A Space Invaders arcade game built from scratch in C++ using the Raylib graphics library. Each game element is implemented as a separate class, structured around a shared abstract base class.

Initially developed as a single-file project and later refactored into a modular object-oriented design using header files. This refactor significantly improved my understanding of OOP design principles and code architecture.

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🚀 Features

• 🚀 Player-controlled spaceship with smooth movement
• 👾 Alien grid that moves side to side and gradually descends
• 🔫 Player shooting mechanics
• 💥 Enemies can fire back, requiring dodging and timing
• 🎯 Collision detection for player and enemy projectiles
• 🏆 Score system (+10 per alien destroyed)
• ❤️ 3 lives before game over
• 🎉 Win condition when all aliens are eliminated
• 💀 Game over screen with restart option
• 🔄 Restart anytime using R
• ⚡ Smooth 60 FPS gameplay loop

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📸 Screenshots

Gameplay

Game Over

🧠 OOP Design

Concept	Implementation
Abstraction	Entity is an abstract base class with pure virtual functions
Inheritance	Spaceship, Alien, Laser, AlienBullets inherit from Entity
Polymorphism	Draw() and Update() are overridden in derived classes
Encapsulation	Core attributes like position and speed are protected within classes
Modular Design	Each class is implemented in separate header files

Class Hierarchy

Entity (abstract base class)
│
├── Spaceship
├── Alien
├── Laser
└── AlienBullets

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📁 Project Structure

Space-Invaders-OOP/
│
├── src/
│   ├── Space_Invaders2.cpp
│   ├── Space_invaders.cpp
│   ├── Entity.h
│   ├── Spaceship.h
│   ├── Alien.h
│   ├── Laser.h
│   ├── AlienBullets.h
│   ├── Game.h
│   ├── Rocket.png
│   └── alien_2.png
│
└── README.md

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🎮 Controls

Key	Action
A / ←	Move left
D / →	Move right
Spacebar	Shoot
R	Restart game
Esc	Quit

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⚙️ How to Run

Requirements

• C++17 compatible compiler (G++)
• Raylib 5.5
• Windows OS

Compile & Run

Using Terminal:

g++ -std=c++17 Space_Invaders2.cpp -o Space_Invaders2 -I. -lraylib -lopengl32 -lgdi32 -lwinmm
./Space_Invaders2

Using VS Code:

1. Open project folder in VS Code
2. Press Ctrl + Shift + B to build
3. Press F5 to run/debug

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👨‍💻 Developer

Kartar Singh CS Student @ IBA Karachi
GitHub: https://github.com/kartar-singh-cs

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📌 Why I Built This

This project was built to go beyond writing functional code and focus on proper software design. It helped me understand object-oriented programming principles such as inheritance, abstraction, and polymorphism.