Projects · Java

Games in Java

Three of them, in the order I built them. Each one added exactly one hard new thing, and the last one is still going. All three are Java and LibGDX with hand-drawn assets, and every line is public.

1. 01

   JPong

   Finished · playable

   Pong, from scratch. The game loop, a velocity vector, and collision that has to feel right rather than merely be correct.

   Learned the shape of a finished game

2. 02

   JPacman

   Finished

   A maze chase where the ghosts genuinely hunt you: breadth-first search across the map, plus chase, frightened and eaten states.

   Learned pathfinding and state machines

3. 03

   Mexveng

   In progress

   A 2D medieval RPG, and the first project big enough that architecture decisions have consequences I have to live with.

   Learning how to sustain a system over time

Project · Java

Mexveng

A 2D medieval RPG in Java and LibGDX. It exists because tutorials end before the hard parts begin - I wanted a codebase big enough that architecture decisions have consequences.

if (keyPressedA()) { dx = -1.0F; }
if (keyPressedD()) { dx = 1.0F; }

public class Player {

    private final InputHandler inputHandler;
    private float dx;
    private float x;
    private float dy;
    private float y;
    private float speed;

    private final Rectangle playerHitbox;

    public Player() {
        speed = 125.0F;
        playerHitbox = new Rectangle(x, y, 32.0F, 32.0F);
        inputHandler = new InputHandler();
    }

    public void update(float deltaTime, Array collisionRects) {
        handleInput();
        x += dx * speed * deltaTime;
        y += dy * speed * deltaTime;
        playerHitbox.setPosition(x, y);
        checkCollision(collisionRects, deltaTime);
    }

    private void checkCollision(Array collisionRects, float deltaTime) {
        for (Rectangle rectangle : collisionRects) {
            if (playerHitbox.overlaps(rectangle)) {
                x -= dx * speed * deltaTime;
                y -= dy * speed * deltaTime;
            }
        }
    }

    private void handleInput() {
        dx = inputHandler.dx();
        dy = inputHandler.dy();
    }
}

Games · 01 · finished

JPong

Two paddles, one ball, sound on every hit. The ball carries a velocity vector and the whole game is what happens when that vector meets something solid. Small enough to finish in a few evenings, which was the point - I wanted the shape of a complete game loop in my hands before attempting a big one.

Play it on itch.io Source on GitHub

public class Ball {

    private static final float INITIAL_SPEED = 200.0F;
    private static final float INITIAL_X = 480.0F;
    private static final float INITIAL_Y = 320.0F;
    private static final float RADIUS = 8.0F;
    private static final float MIN_Y = 32.0F;
    private static final float MAX_Y = 608.0F;

    private final Vector2 position;
    private final Vector2 velocity;
    private final Rectangle bounds;

    public void update(float deltaTime, Rectangle paddle1Bounds, Rectangle paddle2Bounds) {
        position.add(velocity.cpy().scl(deltaTime));
        bounds.x = position.x - RADIUS;
        bounds.y = position.y - RADIUS;

        if (bounds.y <= MIN_Y) {
            velocity.y *= -1;
            position.y = MIN_Y + RADIUS;
        }

        if (bounds.y + bounds.height >= MAX_Y) {
            velocity.y *= -1;
            position.y = MAX_Y - RADIUS;
        }

        if (bounds.overlaps(paddle1Bounds)) {
            playSound.paddleHit1.play(0.7F);
            velocity.x *= -1;
            position.x = paddle1Bounds.x + paddle1Bounds.width + RADIUS;
        }

        if (bounds.overlaps(paddle2Bounds)) {
            playSound.paddleHit1.play(0.7F);
            velocity.x *= -1;
            position.x = paddle2Bounds.x - RADIUS;
        }
    }

    public void reset() {
        position.x = INITIAL_X;
        position.y = INITIAL_Y;

        velocity.x = INITIAL_SPEED;
        velocity.y = INITIAL_SPEED;

        velocity.x *= MathUtils.randomSign();
        velocity.y *= MathUtils.randomSign();
    }
}

The tileset

Drawn by hand, like everything else in these games. Shown enlarged; the real tiles are 16px.

Games · 02 · finished

JPacman

The one I'd show first in an interview. Ghosts don't wander - they run a breadth-first search across the maze and take the first step of the shortest path to you. Three modes on top of that: chase, frightened (run for the corner), and eaten (head home to respawn). The maze is a Tiled map, with walkability read from tile properties rather than hardcoded.

Source on GitHub

private int[] findNextTile(int startColumn, int startRow,
                           int goalColumn, int goalRow,
                           TiledMapTileLayer wallsLayer) {
    Queue<int[]> queue = new LinkedList<>();
    Map<String, int[]> cameFrom = new HashMap<>();

    int[] startTile = {startColumn, startRow};
    queue.offer(startTile);
    cameFrom.put(startColumn + ", " + startRow, null);

    while (!queue.isEmpty()) {
        int[] currentTile = queue.poll();
        int currentColumn = currentTile[0];
        int currentRow = currentTile[1];

        if (currentColumn == goalColumn && currentRow == goalRow) {
            break;
        }

        int[] upNeighbour = {currentColumn, currentRow - 1};
        int[] downNeighbour = {currentColumn, currentRow + 1};
        int[] leftNeighbour = {currentColumn - 1, currentRow};
        int[] rightNeighbour = {currentColumn + 1, currentRow};
        int[][] neighbours = {upNeighbour, downNeighbour, leftNeighbour, rightNeighbour};

        for (int[] neighbour : neighbours) {
            int neighbourColumn = neighbour[0];
            int neighbourRow = neighbour[1];

            if (!isTileWalkable(neighbourColumn, neighbourRow, wallsLayer)) {
                continue;
            }

            String neighbourKey = neighbourColumn + ", " + neighbourRow;
            if (cameFrom.containsKey(neighbourKey)) {
                continue;
            }

            cameFrom.put(neighbourKey, currentTile);
            queue.offer(neighbour);
        }
    }

    int[] tile = {goalColumn, goalRow};
    String tileKey = goalColumn + ", " + goalRow;

    while (cameFrom.get(tileKey) != null
        && (cameFrom.get(tileKey)[0] != startColumn
         || cameFrom.get(tileKey)[1] != startRow)) {
        tile = cameFrom.get(tileKey);
        tileKey = tile[0] + ", " + tile[1];
    }

    return tile;
}

Every sprite drawn by hand

No asset packs. Four ghosts with a frame per direction, both scare states, the player, and the maze tileset. Shown at 4x - they are 16px tiles.

Client work · byjoio

Static first

byjoio is my freelance practice. Clients come to me running on nothing but a social media page, an outdated site from years ago, or no online presence at all. They pay once and leave with a site they own outright - nothing to renew, nothing to subscribe to.

Client names and links live with the clients, not on my portfolio. Ask me and I'll walk you through specific builds.

Client work · pattern

Forms without a backend

Every byjoio site needs a contact form. None of them need a server. This is the pattern that ships on all of them: native validation first, a honeypot for spam, Formspree for delivery, and a fallback that still works when JavaScript doesn't.

const form = document.querySelector('.contact-form');

form.addEventListener('submit', async (event) => {
  event.preventDefault();

  if (form.website.value !== '') {
    return;
  }

  if (!form.reportValidity()) {
    return;
  }

  const button = form.querySelector('[type=submit]');
  button.disabled = true;

  try {
    const response = await fetch(form.action, {
      method: 'POST',
      body: new FormData(form),
      headers: { Accept: 'application/json' },
    });
    if (!response.ok) {
      throw new Error(String(response.status));
    }
    form.hidden = true;
    document.querySelector('.form-sent').hidden = false;
  } catch {
    form.submit();
  }
});

Deep dive · automation

The same process, twice

I have production experience automating business processes in Blue Prism, and I'm moving toward building services in Java. The clearest way to show the difference is to solve one problem both ways.

Skills

Tools

The levels are honest. Daily means I work with it every working day. Working means I ship with it. Building means I'm deliberately investing. Past means a previous role, not current practice. Open a tool to see where it's used on this map.

Not listed: things I've only read about. If it's here, I've built with it.

Background

The long way to Java

Careers read cleaner backwards. This page starts at now and runs downhill into the past - scroll down to go back in time.

1. Now

   Job search: junior Java Developer, Spring Boot

   Not a whim - a convergence. Automation work taught me how business systems fail. The degree and a Spring Boot bootcamp are putting theory under the practice. Mexveng is where the language gets exercised until it's second nature. The rest of this site is the evidence.

2. Ongoing

   BSc Computing & IT, Open University

   Part-time, alongside full-time work. Slower than the standard route and better for it: everything lands on problems I've already met in production, so the theory sticks.

3. Ongoing

   byjoio - freelance web development

   Real clients, real deadlines, real handovers. Freelancing is where I learned that shipping is a skill separate from building - scoping honestly, saying no to features, leaving a client independent rather than dependent.

4. Ongoing

   RPA developer - business process automation

   Work queues, retries, audit trails, across several roles - Blue Prism earlier, different tooling since. The work that taught me how businesses actually run - and exactly where the limits of automating-from-the-outside sit.

5. 2016-2017

   Minecraft modding - first Java

   I wanted the game to do something it didn't, and the only path was code. First classes, first NullPointerException, first time changing a system from the inside. A decade later the tools are better and the reason hasn't changed.

That's the bottom. The only way from here is forward - back to now.

Current

Now

Three tracks, running at once, on purpose.

Day

Job hunting - junior Java Developer (Spring Boot) roles, open to backend generally. Currently working in business process automation.

Night

BSc Computing & IT at the Open University, part-time, plus a Spring Boot bootcamp: Hibernate, JPA, REST and MVC, Spring Security, AOP.

Between

byjoio client work, Mexveng - the Java RPG that keeps the language sharp - and ihavenocards.com, free browser card and pub games for when nobody brought a deck.

Also: more hours in games than I'll admit to, and the odd evening producing techno and DnB. All my web work ships pair programmed with Claude Code - my input and review at every stage.

Contact

One inbox.

Email me or use the form - both land in the same place.

This form is the same pattern every byjoio client site ships - honeypot, native validation, a fallback that works without JavaScript. See how it works.

Code lives at github.com/mjtbase - JPacman and JPong are public. The freelance practice lives at byjoio.co.uk.