Caper

A point-and-click adventure engine built on Phaser 3.

Caper provides the reusable systems for a Humongous-style adventure game: walking, one-click interaction, declarative props, inventory, NPC/cast behavior, weather, cutscenes, transitions, UI helpers, and engine-owned state primitives.

Install

Caper is published to JSR and depends on Phaser 3 as a runtime dependency.

Deno:

deno add jsr:@caper/engine

Node / npm (Vite, webpack, etc.):

npx jsr add @caper/engine
npm install phaser

Usage

Everything is imported from the package entry point:

import { AdventureScene, createAdventureGame } from "@caper/engine";

const game = createAdventureGame({
    scenes: [MyScene],
    // ...game config
});

See the public API for the full list of exports.

Module map

src/ is organized into capability slices. The folders are internal — everything is re-exported from the package root (@caper/engine) — but each slice is "everything for one capability," including the boot-time registry the game fills.

Slice (src/)	What it owns	Modules
core/	cross-cutting primitives	conditions, random, perspective
scene/	the shell a game extends + boots	AdventureScene, EngineScene, createAdventureGame, SubsceneStack, transitions
movement/	locomotion & navigation	WalkController, pathfinding, Fidget, IdleCharacter, behaviors/
interaction/	the one-click verb loop + props	HotspotManager, PropEngine
inventory/	carried items	InventoryLayer, itemDef, ContentRegistry
cast/	NPCs + the ensemble director	NPC, CastDirector, CastRegistry
characters/	playable characters, switching, outfits	CharacterRegistry, CharacterSwitcher, Wearables, portraits
cutscene/	scripted sequences + on-screen speech	Cutscene, CutsceneRunner, cutsceneActor, DialogueBubble, SuccessMessage
environment/	the ambient world	WeatherLayer, NightLayer, CritterHelper
state/	persistent reactive store	Store
assets/	load conventions + engine asset registry	assetLoading, EngineAssets
ui/	shared chrome + dev tools	UIHelper, FullscreenButton, DebugOverlay, SceneEditor

Documentation

Start with docs/index.md.

Useful entry points:

• Architecture
• Hello World
• Props
• Inventory
• NPCs and Cast
• State Store

Local development against an unpublished checkout

To work on a game and the engine side by side without publishing, map the package in your game's deno.json:

{
    "imports": {
        "@caper/engine": "../Caper/mod.js"
    }
}

Development

deno task ci      # lint + fmt:check + check + dts:check + test
deno task test
deno task dts     # regenerate the bundled mod.d.ts from JSDoc

Types

The engine is authored in JavaScript with JSDoc. To ship real types (and satisfy JSR fast-check without --allow-slow-types), deno task dts compiles the JSDoc to declarations with tsc, rolls them into a single self-contained mod.d.ts, and mod.js points at it via // @ts-self-types. deno task dts:check (run in CI) regenerates it and fails if the committed mod.d.ts is stale, so types can never drift from the source.

Publishing

deno task dts && deno publish

Requires the @caper scope on JSR. Pushing a v* tag runs this via .github/workflows/publish.yml.

License

MIT