Overview

pureboard is a library that allows for easy implementation of multiplayer games, by replicating actions on a state. It's designed for boardgame-like games, but can be used for other projects. It uses zustand for state management, so replicated state on client can be easily used in a React project.

How it works?

Clients can send Actions and modify server State, which then will be replicated to other clients. In order for that to work, Reducer function needs to be pure.

1. Creation of a new game causes server to create a State with some id
2. Users can send an Action to the server
3. Server then tries to apply that Action on server's State
   • if it fails (cause that Action describes an invalid move in the game, or user doesn't have permission), applying this Action throws an exception that is sent back to the client, and flow stops here
4. Server then sends this Action to all clients, so they all will apply it, and change their State

Glossary

State - state managed by zustand that has a reducer function which accepts

Action - definition of a move that player can do to change the game state

Reducer - function that gets a State, Action (and optionally some external data), and creates a new State by applying Action on a previous one

User - authenticated user that have an unique userID

Player - games usually have multiple Players/Seats, and one user can be occupy to one or more (that way you can play chess against yourself)

Reducer

Reducer must be a pure function. This is trivial in a games with perfect information, but even in them, you usually have some random elements - like who is the starting player. Also, some games introduce hidden state, that is only visible to a given player (like his hand of cards).

Both of these things are achieved by providing an external data - namely, RandomGenerator and IHiddenObjects