gameface

gameface is a skill for Claude Code, Codex from CitiesSkylinesModding/agents-plugins. It costs 114 tokens per session (2,410 once invoked), scanned A, original, MIT.

Reference knowledge for Gameface, a game-UI system that displays HTML, CSS and JavaScript inside games. It explains how Gameface differs from normal web browsers and which features its embedded engine supports.

In plain words
What is it for?
Use it when writing or debugging a Gameface view, checking whether a web feature is supported, or investigating why HTML, CSS or JavaScript behaves differently inside a game.
Why use it?
Browser-based assumptions can fail because Gameface uses its own HTML and CSS engine with a limited feature set. It also helps account for differences between the documented engine and the older version included in a released game.

Skill for Claude CodeCodex

Part of the coherent-gameface plugin — 2 skills shipped together

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.

agentmods
npx agentmods add skills/citiesskylinesmodding/agents-plugins/gameface
Any agent
npx skills add CitiesSkylinesModding/agents-plugins --skill gameface
Clone the repo
git clone --depth 1 https://github.com/CitiesSkylinesModding/agents-plugins

Made for: Claude Code, Codex.

Or install coherent-gameface, the plugin that ships this one along with the rest of its 2 skills.

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 gameface

README.md
[![agentmods](https://agentmods.dev/badge/skills/citiesskylinesmodding/agents-plugins/gameface.svg)](https://agentmods.dev/skills/citiesskylinesmodding/agents-plugins/gameface)
Your own site
<a href="https://agentmods.dev/skills/citiesskylinesmodding/agents-plugins/gameface"><img src="https://agentmods.dev/badge/skills/citiesskylinesmodding/agents-plugins/gameface.svg" alt="Measured on agentmods" height="20"></a>
Per session 114 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,410 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
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 $0.00114 $0.02410
Opus 5 $0.00057 $0.01205
Sonnet 5 $0.00023 $0.00482
Haiku 4.5 $0.00011 $0.00241

Measured 4d ago against content hash fb154113a06e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

gameface scanned grade A with 1 finding 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 4d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/fetch-doc.mjs), 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

Fallback without node: `curl -s <url>`, then read the HTML between `<main` and `</main>`.
plugins/coherent-gameface/skills/gameface/SKILL.md · 125 lines

How it starts

The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Gameface

Gameface renders game UI from HTML/CSS/JS. It is powered by Cohtml (the HTML engine) and Renoir (the rendering engine), proprietary technology that is not WebKit, Chromium, or Gecko, and not a WebView. JavaScript runs on V8. Gameface implements a deliberate subset of HTML5/CSS3 chosen for game-UI performance: an unsupported HTML element is not an error, it lays out as a generic unstyled flex box with no semantics, and unsupported CSS is silently ignored. (The older Coherent UI product was Chromium-based; search results about it do not describe Gameface.) This skill is written against docs v3.0.3.1, with Cities: Skylines II (CS2) as the worked example throughout.

The map and the territory

The docs are the map; the running game is the territory. Three rules keep them straight:

  1. The docs describe the latest Gameface only. Support tables carry no "since version" annotations. A YES in today's docs is an upper bound, not a fact about your game.
  2. Version-gate every feature claim. A game embeds a Cohtml version frozen at ship time (CS2: 1.64.0.7, while the docs describe a 3.x release). A feature exists in the game iff the changelog introduced it at or below the game's version. references/version-gating.md has the lookup procedure, a baked version-to-feature timeline, and the list of features that never existed at all.
  3. Probe the territory. Two games on the same Cohtml version can still differ: per-game compatibility flags and embedder choices gate complex-selector styling, WebSockets, localization, text-transform, and more. When a game is reachable, game_status reports the engine version (the CDP endpoint answers Browser: "Cohtml/x.y.z"), and game_eval settles support questions in one probe: typeof ResizeObserver for APIs, a style round-trip for CSS (el.style.setProperty('gap', '4px') then read it back; the parser rejects unsupported values, so they read back empty). CSS.supports does not exist (the CSS global is only unit factories like CSS.px). Page JS has no version global, but navigator.userAgent carries the engine version; sniff it for the version, feature-detect everything else.

Read the full file on GitHub · 125 lines

Files

What ships with it

6 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. 4d ago First seen · 125 lines · 114 tokens per session scan A fb154113a06e

Subscribe to this mod's changes

gameface is a skill published in the GitHub repository CitiesSkylinesModding/agents-plugins (5 stars, last pushed 4d ago), licensed MIT. It adds 114 tokens to every session and 2,410 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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