vertical-slice

vertical-slice is a skill for Claude Code from Donchitos/Claude-Code-Game-Studios. It costs 66 tokens per session (3,804 once invoked), scanned A, original, MIT.

A production-quality test build of one complete game loop, from starting a challenge through reaching its resolution. It is used to check whether the game can be produced at the intended quality before full production begins.

In plain words
What is it for?
Use it after the game design documents, architecture, and UX specifications are ready to decide whether to proceed, change direction, or stop.
Why use it?
It exposes problems with the development pipeline, technical decisions, schedule, or the game experience before the team commits to building everything.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: model in frontmatter; mentions CLAUDE.md; names the AskUserQuestion tool.

Good fit Use it after the game design documents, architecture, and UX specifications are ready to decide whether to proceed, change direction, or stop.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/donchitos/claude-code-game-studios/vertical-slice
About the project

Claude Code Game Studios is a setup that organizes Claude Code into a coordinated game-development team of specialized AI agents. It supports game projects across design, programming, art, audio, narrative, quality assurance, and production, with skills and workflows for coordinating that work.

Donchitos/Claude-Code-Game-Studios · 24,852 stars · on GitHub

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 Donchitos/Claude-Code-Game-Studios --skill vertical-slice
Clone the repo
git clone --depth 1 https://github.com/Donchitos/Claude-Code-Game-Studios

Made for: Claude Code.

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 vertical-slice

README.md
[![agentmods](https://agentmods.dev/badge/skills/donchitos/claude-code-game-studios/vertical-slice.svg)](https://agentmods.dev/skills/donchitos/claude-code-game-studios/vertical-slice)
Your own site
<a href="https://agentmods.dev/skills/donchitos/claude-code-game-studios/vertical-slice"><img src="https://agentmods.dev/badge/skills/donchitos/claude-code-game-studios/vertical-slice.svg" alt="Measured on agentmods" height="20"></a>
Per session 66 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,804 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 warn 7 Sept 2026
SkillSpector: 1 finding, up to medium
  • medium Excessive Agency · line 7
    Skill selects an external model or provider that may use a different account or billing plan than the operator expects. Undisclosed model switches can cause unexpected cost or quota consumption.
    Fix: Remove the model/provider override or disclose it prominently and require explicit operator approval before invoking an external coding CLI or billed model.
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 $0.00066 $0.03804
Opus 5 $0.00033 $0.01902
Sonnet 5 $0.00013 $0.00761
Haiku 4.5 $0.00007 $0.00380

Measured 4d ago against content hash a555d5a79fce, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

vertical-slice 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 4d ago.

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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.claude/skills/vertical-slice/SKILL.md · 360 lines

How it starts

The opening of the file, as written. The whole thing — 360 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Purpose

The vertical slice answers a different question from the concept prototype: "Can we build this full game loop at production quality, on schedule?"

Default use — run late in Pre-Production, after GDDs, architecture, and UX specs are complete. It is a near-production-quality build demonstrating one complete [start → challenge → resolution] cycle.

Post-pivot? If a PIVOT verdict from an earlier vertical slice sent you back to revise GDDs and architecture, run this again after revisions to re-validate. It can be run as many times as needed until a PROCEED or KILL verdict is reached.

It validates:

  1. The pipeline (can the team actually produce this quality of content?)
  2. Execution feasibility (are the architecture decisions correct for this game?)
  3. Fun survival (does the fun from the concept prototype survive full design?)
  4. Velocity (how long did this take? That's your real production rate estimate.)

Earlier in the project? If you haven't written GDDs yet and want to validate whether the core idea is worth designing, run /prototype (concept prototype) instead.


Phase 1: Resolve Review Mode and Load Context

Resolve the review mode:

  1. If --review [full|lean|solo] was passed → use that
  2. Else read production/review-mode.txt → use that value
  3. Else → default to lean

See .claude/docs/director-gates.md for the full check pattern.

Read the following files to understand the full design intent:

  • CLAUDE.md — tech stack and engine
  • design/gdd/game-concept.md — core fantasy and game pillars
  • design/gdd/systems-index.md — MVP systems and their priorities
  • docs/architecture/architecture.md — layer structure
  • docs/architecture/control-manifest.md — technical rules for implementation
  • Key GDDs for the systems being sliced

Phase 2: Define the Slice Scope and Validation Question

Before building, define the falsifiable validation question:

"Does a player, starting from nothing, experience [core fantasy from game-concept.md] within [N] minutes, without developer guidance — and can we build one such loop in [X] days at representative quality?"

Read the full file on GitHub · 360 lines

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 · 360 lines · 66 tokens per session scan A a555d5a79fce

Subscribe to this mod's changes

vertical-slice is a skill published in the GitHub repository Donchitos/Claude-Code-Game-Studios (24,852 stars, last pushed 3mo ago), licensed MIT. It adds 66 tokens to every session and 3,804 once invoked, about $0.0003 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 2026-09-03.