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Getting started

You need Flutter installed and enough Dart to read a class. You do not need to have built a game before.

What a game is made of here

Four ideas, and that is the whole model:

  • Entities are the things in your game: a player, a bullet, a tree. An entity is a number, and its data lives in columns beside it.
  • Prefabs say what a kind of entity is made of — a player has a position, a sprite and a speed.
  • Scenes say what exists when the game starts.
  • Systems are where behaviour goes: code that runs every step of the simulation, over every entity that matches what it asked for.

So a game is: declare the kinds of thing, declare what exists, write the code that moves them. Nothing inherits from anything, and you never write a game loop — the engine runs one and calls your systems from it.

If you have used Unity, Godot or Flame, some of that will look familiar and some of it will not. Coming from Unity, Godot or Flutter is the translation table: the call you would have written and its replacement, side by side. Thinking in ECS then takes the habits you already have and shows where each one lands, including the ones that have no home here.

Three pages, in the order you meet them

  1. Installation — the Flutter SDK, the per-platform native toolchains, and putting good on your PATH.
  2. Create a project — good create, what it writes, and how a good project is configured.
  3. Your first game — a sprite driven by the keyboard, built up from the empty scaffold.

By the end of the third page you have something you can run and move around.

A note on the code you will see

Every example uses goo2d, the 2D engine. Scenes, prefabs, systems, input and assets come from the kernel underneath it, so a 3D game writes those the same way; only the transform, sprite and camera types differ. The axes agree too — both put +Y up, so a system that moves something upward keeps meaning that when you carry it into 3D. See 2D and 3D if you want the whole picture first.

Words like prefab, archetype and isolate have a dotted underline wherever they appear — hover for a one-line definition rather than going to look it up.

If you would rather understand the engine before writing any of it, start with Architecture.