🛸 Space Invaders - Java Swing Game

Overview

This is a simple implementation of the classic arcade game Space Invaders built using Java Swing. The player controls a spaceship at the bottom of the screen, shooting bullets to destroy descending waves of alien invaders. The game features progressive difficulty, scoring, and a game over condition when aliens reach the player's level.

Key features:

• Player spaceship movement (left/right) and shooting (spacebar).
• Alien waves that move horizontally and descend upon hitting screen edges.
• Collision detection between bullets and aliens.
• Score tracking with bonus points for clearing waves.
• Increasing difficulty: More aliens and rows as levels progress.
• Game restart on any key press after game over.

The game uses colored rectangles for graphics (no external images required) to keep it lightweight and self-contained.

Screenshots

In-Game (Active Play)

(Shows the player ship (cyan rectangle) at the bottom, green alien rectangles moving across the top, white bullets firing, and current score displayed.)

Game Over

(Displays "Game Over: 7600" score with remaining aliens visible. Press any key to restart.)

(Note: Screenshots are based on the running game; actual visuals use simple colored shapes for ship (cyan), aliens (green), and bullets (white).)

Requirements

• Java Development Kit (JDK) 8 or higher.
• No external libraries or assets needed.

How to Run

1. Clone or download the project files (SpaceInvaders.java and App.java).
2. Compile the code:

   javac SpaceInvaders.java App.java
   

3. Run the application:

   java App
   

4. The game window (512x512 pixels) will open automatically.

Controls

• Left Arrow (←): Move ship left.
• Right Arrow (→): Move ship right.
• Spacebar: Shoot a bullet.
• Any Key: Restart the game after "Game Over".

Game Mechanics

• Aliens: Start with 2 rows and 3 columns of aliens. They move left/right and descend when hitting the screen edges. Destroy all to advance to the next level (more aliens added).
• Bullets: Fired from the ship; travel upward and disappear on alien hit or off-screen.
• Scoring:
  • 100 points per alien destroyed.
  • Bonus: 100 points × (rows × columns) for clearing a wave.
• Game Over: Triggers if any alien reaches the ship's Y-level.
• Difficulty: Alien columns cap at 6, rows at 10. Movement speed is fixed but wave density increases.

Code Structure

• SpaceInvaders.java: Core game logic.
  • Block inner class: Represents game objects (ship, aliens, bullets) with position, size, and state.
  • paintComponent and draw: Renders graphics using Graphics (rectangles for simplicity).
  • move: Updates positions, handles collisions, and level progression.
  • actionPerformed: Game loop (60 FPS timer).
  • keyReleased: Handles input.
• App.java: Entry point; sets up the JFrame and adds the game panel.

The code is modular, with clear separation of drawing, movement, and input handling. Collision detection uses simple rectangle overlap checks.

Potential Improvements

• Add sound effects (using javax.sound).
• Introduce alien shooting or varied enemy types.
• Power-ups or multiple lives.
• High score persistence (file I/O).

License

This project is open-source and free to use/modify. Created for educational purposes.

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Built with ❤️ using Java Swing. Inspired by the 1978 Atari classic.