building-mobile-game

building-mobile-game is a skill for Codex from Intelligent-Internet/ii-agent. It costs 91 tokens per session (1,100 once invoked), scanned A, original, Apache-2.0.

A workflow for creating mobile games and game-like experiences with React Native and Expo, a toolkit for building mobile apps with JavaScript or TypeScript.

In plain words
What is it for?
It helps build or refactor arcade, puzzle, casual, action, and physics-based games, including game loops, sprite sheets, animation frames, and Expo setup.
Why use it?
It provides rules for setting up gameplay, animation, physics, assets, and performance in one consistent process.

Skill for Codex

Written for Codex: agents/openai.yaml present. Also seen: mentions Codex.

Good fit It helps build or refactor arcade, puzzle, casual, action, and physics-based games, including game loops, sprite sheets, animation frames, and Expo setup.

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Install with agentmods
npx agentmods add skills/intelligent-internet/ii-agent/building-mobile-game
About the project

II-Agent is an open-source framework and AI agent for building applications, conducting research, and automating workflows from natural-language prompts. Developers, research teams, and enterprises use it to create mobile apps, websites, illustrated books, media, research outputs, and integrations with external services. The catalogue skills and instructions provide workflows and integrations for using II-Agent.

Intelligent-Internet/ii-agent · 3,382 stars · on GitHub · ii.inc

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add Intelligent-Internet/ii-agent --skill building-mobile-game
Clone the repo
git clone --depth 1 https://github.com/Intelligent-Internet/ii-agent

Made for: Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for building-mobile-game

README.md
[![agentmods](https://agentmods.dev/badge/skills/intelligent-internet/ii-agent/building-mobile-game/github.svg)](https://agentmods.dev/skills/intelligent-internet/ii-agent/building-mobile-game)
Your own site
<a href="https://agentmods.dev/skills/intelligent-internet/ii-agent/building-mobile-game"><img src="https://agentmods.dev/badge/skills/intelligent-internet/ii-agent/building-mobile-game/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for building-mobile-game

Your own site · 80×15
<a href="https://agentmods.dev/skills/intelligent-internet/ii-agent/building-mobile-game"><img src="https://agentmods.dev/badge/skills/intelligent-internet/ii-agent/building-mobile-game.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 91 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,100 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00091 $0.01100
Opus 5 $0.00046 $0.00550
Sonnet 5 $0.00018 $0.00220
Haiku 4.5 $0.00009 $0.00110

Measured 11d ago against content hash 6039c4292e51, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

building-mobile-game scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/extract_sprites.py, scripts/normalize_animation_frames.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

src/ii_agent/settings/skills/builtin/building-mobile-game/SKILL.md · 68 lines

How it starts

The opening of the file, as written. The whole thing — 68 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Mobile Game Workflow

References

  • ./references/setup-and-loop.md -- Expo bootstrap, worklets setup, engine selection, game loop order, physics rules, packages, and performance checks
  • ./references/assets-and-animation.md -- sprite-sheet prompt templates, extraction workflow, naming, animation state mapping, and validation checklist
  • ./scripts/extract_sprites.py -- connected-component sprite extractor with background removal and optional frame normalization
  • ./scripts/normalize_animation_frames.py -- shared-scale frame normalizer with optional anchor frame locking for existing characters

Mandatory Reading Order

For any new mobile game task, read both reference files before planning implementation or calling project tools:

  1. Read ./references/setup-and-loop.md first.
  2. Read ./references/assets-and-animation.md second.
  3. Only after both references have been read should you choose libraries, plan gameplay, generate assets, or start coding.

Do not stop after reading only setup-and-loop.md. The asset reference is also mandatory for almost every real game because it covers sprite-sheet prompting, extraction, and normalization.

The only acceptable exception is a deliberately art-free prototype that uses simple geometric placeholder shapes and no image generation. When in doubt, read both references anyway.

Quick Start

  1. Read ./references/setup-and-loop.md, then read ./references/assets-and-animation.md.
  2. Start from mobile_app_init(..., example="with-reanimated", with_tailwind=False) for animation-heavy or gesture-heavy game projects.
  3. Install [email protected] and put "react-native-worklets/plugin" last in babel.config.js. Never add "react-native-reanimated/plugin".
  4. Choose the lightest rendering stack that can support the mechanic:
    • react-native-game-engine for most 2D arcade or puzzle loops
    • @shopify/react-native-skia for custom 2D drawing and effects
    • expo-gl plus three for 3D or GL scenes
    • matter-js only when the game truly needs richer physics
  5. Build gameplay in this order: input, movement, collisions, scoring or lives, pause or restart, then polish.
  6. Ask generate_image for one whole animation strip at once, not one frame at a time, so character identity and proportions stay consistent.
  7. Split raw strips with ./scripts/extract_sprites.py, then standardize them with ./scripts/normalize_animation_frames.py when the game needs fixed frame sizes or an exact existing idle anchor.
  8. Verify the game on Expo web and on mobile before calling the feature done.

Read the full file on GitHub · 68 lines

Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 11d ago First seen · 68 lines · 91 tokens per session scan A 6039c4292e51

Subscribe to this mod's changes

building-mobile-game is a skill published in the GitHub repository Intelligent-Internet/ii-agent (3,382 stars, last pushed 25d ago), licensed Apache-2.0. It adds 91 tokens to every session and 1,100 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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