Overview

This section states how a build writes its code against Simple 2D: the shape of a build, the worked examples, and the idioms the engine expects. Every example here is game-side code.

The engine ships its own documentation inside its package. Seeding copies that directory into the run workspace at engine/, and the rendered prompt names the engine and points the build at it, so a model builds against the same contract this section states. These pages are the developer-facing statement of it.

The division

The build supplies one Game<S, D>. Its initialize declares the action bindings, cue definitions, assets, and diagnostic sources the game needs and returns the state beside the debug surface, as [state, debug]; its update returns the next state from the current one and the frame’s delta; its render draws the state in logical coordinates.

The engine owns everything around that: the frame loop and the clock behind its delta time, the canvas fit, keyboard listening and edge detection, the audio graph and its unlock, asset resolution, and the overlay.

The state is the only channel between the three functions. The engine holds it as a value: each frame it hands the current state to update as a read-only view, keeps what update returns, and hands that to render. A build reaches for its own module-level variables only for constants.

Pages

Page	Covers
Creating the Engine	The design size, the options createEngine takes, sizing the canvas from CSS, choosing a clock, and teardown.
The Game Loop	Writing initialize, update, and render, booting the engine, integrating against delta time, pausing, and ending a run.
Drawing	Drawing in logical coordinates, the cleared frame, and reading the pointer.
Actions	Registering actions, reading held values and edges, and selecting a touch layout.
Audio and Assets	Defining and loading cues, playing them from update, and loading assets under the asset root.
Diagnostics	Registering overlay sources and choosing what a case’s checks can read.
Debug Surface	Declaring the surface type, writing its poses and readings over the state, exposing it from initialize, and driving it through engine.apply and engine.state.