Diamond Hunter – Java 2D Game

Introduction

There’s something incredibly satisfying about building a game without a game engine.
No Unity. No Unreal.
Just Java, Swing, and your own logic.
When I found this project — a 2D tile-based game from scratch — I knew I had to try it.
It’s simple on the surface:
move a character
collect diamonds
avoid enemies

But underneath, it teaches everything that matters:
game loops, rendering, input, and basic architecture.
This tutorial by ForeignGuyMike is a great starting point:
👉 Diamond Hunter – Java 2D Game (with source code)

🧩 0. What you’ll build

A small 2D game with:

• Player movement (up/down/left/right)
• Tile-based map
• Collectible diamonds
• Enemies
• Simple collision system
• Camera that follows player

🛠️ 1. Setup your environment

Install tools

Install Java JDK (17 or newer)
Install IntelliJ IDEA (recommended) or VS Code
Create a new Java Project

📁 2. Project structure

Create this folder structure:

src/
 ├── main/
 │    ├── GamePanel.java
 │    ├── KeyHandler.java
 │    ├── Main.java
 ├── entity/
 │    ├── Player.java
 ├── tile/
 │    ├── Tile.java
 │    ├── TileManager.java

🧠 3. Game loop (core engine)

Main.java

public class Main {
    public static void main(String[] args) {
        new GamePanel();
    }
}

GamePanel.java (window + loop)

import javax.swing.*;
import java.awt.*;

public class GamePanel extends JPanel implements Runnable {

    final int tileSize = 48;
    final int screenCol = 16;
    final int screenRow = 12;

    Thread gameThread;

    public GamePanel() {
        this.setPreferredSize(new Dimension(tileSize * screenCol, tileSize * screenRow));
        this.setBackground(Color.BLACK);
        this.setDoubleBuffered(true);
    }

    public void startGameThread() {
        gameThread = new Thread(this);
        gameThread.start();
    }

    @Override
    public void run() {
        while (gameThread != null) {
            update();
            repaint();
        }
    }

    public void update() {
        // update player, enemies
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        // draw world
    }
}

🎮 4. Player movement

KeyHandler.java

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

public class KeyHandler implements KeyListener {

    public boolean up, down, left, right;

    public void keyPressed(KeyEvent e) {
        int code = e.getKeyCode();

        if (code == KeyEvent.VK_W) up = true;
        if (code == KeyEvent.VK_S) down = true;
        if (code == KeyEvent.VK_A) left = true;
        if (code == KeyEvent.VK_D) right = true;
    }

    public void keyReleased(KeyEvent e) {
        int code = e.getKeyCode();

        if (code == KeyEvent.VK_W) up = false;
        if (code == KeyEvent.VK_S) down = false;
        if (code == KeyEvent.VK_A) left = false;
        if (code == KeyEvent.VK_D) right = false;
    }

    public void keyTyped(KeyEvent e) {}
}

Player.java

public class Player {

    int x = 100;
    int y = 100;
    int speed = 4;

    KeyHandler keyH;

    public Player(KeyHandler keyH) {
        this.keyH = keyH;
    }

    public void update() {
        if (keyH.up) y -= speed;
        if (keyH.down) y += speed;
        if (keyH.left) x -= speed;
        if (keyH.right) x += speed;
    }
}

🧱 5. Tile system (map rendering)
Tile.java

import java.awt.image.BufferedImage;

public class Tile {
    BufferedImage image;
    boolean collision = false;
}

TileManager.java
Handles:

• Loading tile images
• Drawing map
• Collision tiles

Concept:

int[][] map = {
    {1,1,1,1},
    {1,0,0,1},
    {1,0,0,1},
    {1,1,1,1}
};

💎 6. Add diamonds (collectibles)

Create:

entity/Diamond.java

Logic:

• Place diamonds in map
• When player touches → remove + score++

👾 7. Add enemies

Basic enemy:

public class Enemy {

    int x, y;
    int speed = 2;

    public void update() {
        // simple random movement or chase player
    }
}

Add collision:

If player touches enemy → reset or lose life

📷 8. Camera system

Instead of moving player across screen:

• Keep player centered
• Move world (tiles + objects)

🎨 9. Rendering (draw everything)

Inside paintComponent():

tileManager.draw(g);
player.draw(g);
for (Diamond d : diamonds) d.draw(g);

🔊 10. Polish

Add:

• Sound (Java Clip API)
• Sprite animations
• UI (score, health)

🚀 11. Run your game

In Main:

JFrame window = new JFrame();
window.add(new GamePanel());
window.pack();
window.setVisible(true);

---

🧠 Important insight

The video’s game works because of:

• Game loop (update + draw)
• Tile-based world
• Entity system (player, enemies, items)

These are foundational concepts used in most 2D games.

Next Step

Turn this into a full working downloadable project