SpriteDX - Playground - Multiplayer Design v0.1

This document will discuss how to implement playground system that allows for network based games.

Vision

Build a minimal, session-based shared world where players coexist in real time — move, collide, emote, and interact — with FPS-grade responsiveness, near-zero idle cost, and an architecture so clean it feels inevitable.

Motivation

Most multiplayer system fail one of three ways:

1. Overbuilt

2. Over-managed

3. Over-locked

As a single-person startup, the goal is to design a system that:

• Scales down better than it scales up

• It understandable in one sitting

• Can be abandoned for months and restarted cleanly

• Feels elegant rather than clever

Core Goals

1. Real-time coexistence
   FPS-style movement and interactions
   Server-authoritative
   4-16 players per session

2. Scale-to-zero cost
   No idle compute
   No permanent game servers
   Pay only while a session is alive

3. 10-year survivability
   Open protocols
   portable infra
   No black-box multiplayer SDKs

4. Solo-founder operability
   Few moving parts
   Easy debugging
   clear failure modes

5. Character-first
   Characters are external data (SpriteDX)

Non-Goals

• No persistent world state

• No economy

• No MMO scaling

• No kernel anti-cheat

• No platform lock-in wars

High-Level Architecture

   [Browser Client (Unity WebGL)]
                |
                | WebRTC / UDP-like Transport
                |
  [Ephemeral Authoritative Game Server]
                |
  [Control Plane (Matchmaking + Auth)]
                |
  [Asset/CDN (SpriteDX Characters)]

Technical Decisions

Client

• Unity WebGL

• Client-side predictions + reconciliation

• Characters loaded dynamically via manifest

Networking

• WebRTC DataChannels

  • Browser-safe

  • UDP semantics

  • NAT traversal handled

• 30-60 Hz tick

Game Server

• Authoritative

• Stateless per match

• Runs physics + hit validation

• Lifespan = session duration

Hosting Model

• Ephemeral compute

  • Spins up on match start

  • Destroy on match end

• No always-on instances

Control Plane

• Simple HTTP / WebSocket service

• Matchmaking

• Session orchastration

• Can live on:

  • Cloudflare Workers

  • Any boring backend

Character Model

{
  "characterId": "spritedx:pixel_042",
  "animations": {
    "idle": "idle.webp",
    "run": "run.webp",
    "jump": "jump.webp"
  },
  "hitbox": { "w": 0.6, "h": 1.8 },
  "scale": 1.0
}

• Hot-loadable

• Cacheable

• Portable across worlds

• Identity follows the character

This is the emotional core.

— Pixel