OpenMon

A fan-made, web-based Pokemon game in 2.5D, built entirely on the client side with no backend. The overworld is rendered in 3D using Three.js/Threlte while battles and menus use a 2D sprite-based approach. This project is for educational purposes only.

Play OpenMon

Features

• 2.5D Overworld -- 3D tile-based world with billboard sprites, dynamic camera, and weather particles
• Turn-based Battles -- type effectiveness, abilities (150+), held items, status conditions, weather, terrain, and entry hazards
• Pokedex -- viewed/caught tracking across 600+ Pokemon species
• Dungeon Mode -- procedurally generated floors with seeded RNG, biome-based encounters, boss battles, and meta progression
• Item System -- bag inventory, held items with battle effects, Pokeball catching
• Pokemon Storage -- PC box system with drag-and-drop management
• Quest & Script Engine -- NPC dialogues, quests with objectives, and map-triggered events
• Evolution & Experience -- leveling, nature system, IVs/EVs, and evolution chains
• Pokemon Followers -- a Pokemon from your party follows you in the overworld
• Save/Load -- multiple save slots persisted to localStorage
• PWA Support -- installable as a Progressive Web App for offline play
• Admin Panel -- developer tools for testing Pokemon, animations, and evolution

Technology Stack

Directory Structure

src/
├── App.svelte          # Main router
├── main.ts             # Entry point
├── app.scss            # Global styles
├── js/                 # Game logic & models
│   ├── __tests__/      # Unit tests (100+)
│   ├── battle/         # Battle system (abilities, actions, animations, items)
│   ├── characters/     # Player, NPC, follower models
│   ├── commands/       # Input controls, joystick
│   ├── context/        # Game/Battle/Overworld contexts + managers
│   ├── dungeon/        # Dungeon system (procedural generation, biomes)
│   ├── items/          # Item definitions and bag
│   ├── lighting/       # Biome lighting configuration
│   ├── mapping/        # Maps, collisions, Threlte map conversion
│   ├── pokemons/       # Pokedex, moves, effects, experience
│   ├── scripting/      # Scripts, quests, notifications
│   └── sprites/        # Sprite management
├── lib/                # Svelte UI components (70+)
│   ├── admin/          # Admin panel (dev tools)
│   ├── battle/         # Battle screen and action bar
│   ├── common/         # Shared components (Modal, DialogView, etc.)
│   ├── debug/          # Debug/test pages
│   ├── menus/          # Game menus (Pokedex, Bag, Pokemon list, Boxes)
│   ├── saves/          # Save/Load components
│   ├── world/          # Overworld controls and HUD
│   └── world3d/        # 3D world rendering (Threlte/Three.js)
└── assets/             # Images, audio, JSON data

Getting Started

Prerequisites

Node.js (LTS recommended)

Run Locally

npm install
npm run dev

This starts a dev server at http://localhost:5173/

Build

npm run build

Creates a dist folder with production files. The output is also copied to docs/ for GitHub Pages deployment.

Test

npm run test:run    # Run unit tests once
npm run test        # Run tests in watch mode
npm run test:e2e    # Run Playwright end-to-end tests

Deploy

Pushing to master automatically deploys to GitHub Pages.

Credits

All resources (images, sounds, names) are owned by Nintendo and The Pokemon Company. This project makes no commercial claims.

• Pokemon data from PokeAPI (downloaded CSVs, exported to JSON)
• Formulas and mechanics from Bulbapedia and Pokepedia

Contributing

Contributions are welcome. Feel free to open an issue or pull request.

Please follow the coding standards described in AGENTS.md, which covers code style (Prettier config), naming conventions, Svelte 5 patterns, and directory organization.

License

MIT