Custom

---
name: custom
description: Use when a proprietary or custom game loop needs open-game-skills contracts mapped onto its actual simulation, rendering, input, collision, animation, and pause architecture.
---

# Custom engine adapter

First document the runtime/engine version or build identity and the existing loop. Do not invent a 60 Hz clock merely because other engines often expose fixed-step patterns.

## Timing contract

Publish the project's actual simulation model: fixed step, variable step, multiple rates, lockstep, server-authoritative, or another explicit design. If a fixed step exists, record its configured duration/rate and catch-up/drop policy. Keep render interpolation and presentation callbacks separate from authoritative gameplay state.

Map these responsibilities conceptually rather than forcing a specific function signature:

- semantic input sampling;
- logical tick/time identity;
- actor pose/animation presentation;
- gameplay contact queries;
- collision-safe movement/knockback;
- presentation/juice events.

Per-actor hitstop freezes only the named logical/action clocks. A separate global pause may freeze broader systems when the project explicitly owns that behavior.

## Lifecycle and resources

The engine-neutral rules live in `audio-feel`, `juice-vfx`, `asset-runtime`, `performance-budget` and `soak-stability`; this section only maps them onto a custom runtime. Document:

- the audio-output availability states (locked, device lost, background) and where cues are dropped or fall back;
- the focus/background/suspend/device-loss hooks and the catch-up limit applied on resume;
- the pools/arenas for frequently spawned effects and voices, and the release point of every engine/GPU/audio handle;
- the overlay draw order relative to HUD-critical elements.

Camera anti-clip follows `camera-anti-clip`: protect the actual camera/frustum footprint and final offsets rather than relying on a single point ray.

## Asset pack import

A validated asset pack is plain images, JSON and audio, so any runtime can consume it: read the manifest, load atlas JSON (frame rectangle, source size, trim offset, pivot, tick holds, animation lists), read Tiled `.tmj`/`.tsj` (row-major gid arrays, gid minus one as tile id, tile `type` as semantics, objects anchored at their tile bottom) and the feel/box/enemy/audio data files. Keep the pack's declared logical clock separate from render frequency, render the profile's virtual resolution (`data/display.json`) to an offscreen target and blit it to 1920x1080 at the declared integer scale with nearest filtering for pixel styles (linear for the native 1080p cartoon style, never a fractional scale), resolve every asset through `styles.json` so one style id swaps the whole visual layer (atlas rectangles or GLB node and clips) while levels, tile-unit hitboxes and ticks stay the same, and record the loader build and what it reproduced as import evidence.

## Accept

Record engine/runtime build identity, loop diagram, configured clock rates, phase order and pause ownership. Replay a deterministic input/contact trace at at least two render cadences where the runtime permits; logical results must match, and untested timing modes remain `not-run`.

Record the lifecycle hooks and resource release points used. A burst, teardown and background/resume cycle returns live effect, voice, timer and handle counts to the warm-up baseline; untested platforms remain `not-run`.