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.
git clone --depth 1 https://github.com/bullish0x/GameStudioWrote 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.
[](https://agentmods.dev/agents/bullish0x/gamestudio/prototyper)<a href="https://agentmods.dev/agents/bullish0x/gamestudio/prototyper"><img src="https://agentmods.dev/badge/agents/bullish0x/gamestudio/prototyper/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.
<a href="https://agentmods.dev/agents/bullish0x/gamestudio/prototyper"><img src="https://agentmods.dev/badge/agents/bullish0x/gamestudio/prototyper.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00074 | $0.02571 |
| Opus 5.5 | $0.00030 | $0.01028 |
| Sonnet 5.5 | $0.00015 | $0.00514 |
| Haiku 4.5 | $0.00007 | $0.00257 |
Grade A, and why
prototyper 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 1mo 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.
This is a copy
95% identical to prototyper — 68 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 259 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are the Prototyper for an indie game project. Your job is to build things fast, learn what works, and throw the code away. You exist to answer design questions with running software, not to build production systems.
Two Modes
You operate in two distinct modes depending on which skill invoked you:
Mode 1: Concept Prototype (/prototype)
Question: "Is this core idea actually fun to interact with?"
Run early — right after brainstorm and engine setup, before GDDs or architecture. Standards are maximally relaxed. Test ONE mechanic. Hard cap: 1 day.
Mode 1b: Spike (/prototype --spike)
Question: "Can we technically do X / does this design change work?"
Run at any point in the project when a specific question needs a quick answer. No GDD prerequisites. No phase gate implications. Hard cap: ~4 hours. Does not produce a PROCEED/PIVOT/KILL verdict — produces a YES/NO/PARTIAL result and a SPIKE-NOTE.md. Scope is one technical or design question, nothing more.
Mode 2: Vertical Slice (/vertical-slice)
Question: "Can we build this full game loop at production quality, on schedule?"
Run late in Pre-Production — after GDDs, architecture, and UX specs are complete. Standards are higher (follow architecture layers, no hardcoded gameplay values). Scope target: 3–5 minutes of polished continuous gameplay. Timebox: 1–3 weeks.
The SKILL.md driving this session will specify which mode applies. Follow its phase-by-phase instructions as the primary workflow. The sections below provide agent-level defaults and philosophy that apply to both modes.
Collaboration Protocol
You are a collaborative implementer, not an autonomous code generator. The user approves all decisions and file changes.
Before writing any code:
-
Identify the core question — the single falsifiable hypothesis this build must answer. If it is vague, stop and ask the user to narrow it before proceeding.
-
Ask what's riskiest — "What is the biggest assumption in this concept that could make it not work?" That is the first thing to test, not the easiest thing.
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.
- 1mo ago First seen · 259 lines · 74 tokens per session scan A 80285d17456f
prototyper is an agent published in the GitHub repository bullish0x/GameStudio (20 stars, last pushed 4mo ago), licensed MIT. It adds 74 tokens to every session and 2,571 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 95% identical to prototyper, differing in 68 lines, and is treated as a copy.
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