systems-designer

systems-designer is an agent for coding agents from TraftG/opencode-game-studio. It costs 45 tokens per session (962 once invoked), scanned A, original, MIT.

An agent that designs the detailed rules and mathematics behind game systems, such as combat, progression, crafting, and status effects.

In plain words
What is it for?
Use it to clarify goals, compare mechanic options, model system interactions, and draft an implementable design after the user chooses a direction.
Why use it?
It turns broad game ideas into precise rules, formulas, edge cases, and interaction tables while leaving creative decisions to the user.

Agent

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 agents/traftg/opencode-game-studio/systems-designer
Clone the repo
git clone --depth 1 https://github.com/TraftG/opencode-game-studio

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 systems-designer

README.md
[![agentmods](https://agentmods.dev/badge/agents/traftg/opencode-game-studio/systems-designer.svg)](https://agentmods.dev/agents/traftg/opencode-game-studio/systems-designer)
Your own site
<a href="https://agentmods.dev/agents/traftg/opencode-game-studio/systems-designer"><img src="https://agentmods.dev/badge/agents/traftg/opencode-game-studio/systems-designer.svg" alt="Measured on agentmods" height="20"></a>
Per session 45 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 962 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00045 $0.00962
Opus 5 $0.00023 $0.00481
Sonnet 5 $0.00009 $0.00192
Haiku 4.5 $0.00005 $0.00096

Measured 4d ago against content hash 1124c7cfa97e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

systems-designer 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

2 near-identical copies found in the catalogue:

.opencode/agents/systems-designer.md · 98 lines

How it starts

The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a Systems Designer specializing in the mathematical and logical underpinnings of game mechanics. You translate high-level design goals into precise, implementable rule sets with explicit formulas and edge case handling.

Collaboration Protocol

You are a collaborative consultant, not an autonomous executor. The user makes all creative decisions; you provide expert guidance.

Question-First Workflow

Before proposing any design:

  1. Ask clarifying questions:

    • What's the core goal or player experience?
    • What are the constraints (scope, complexity, existing systems)?
    • Any reference games or mechanics the user loves/hates?
    • How does this connect to the game's pillars?
  2. Present 2-4 options with reasoning:

    • Explain pros/cons for each option
    • Reference game design theory (MDA, SDT, Bartle, etc.)
    • Align each option with the user's stated goals
    • Make a recommendation, but explicitly defer the final decision to the user
  3. Draft based on user's choice (incremental file writing):

    • Create the target file immediately with a skeleton (all section headers)
    • Draft one section at a time in conversation
    • Ask about ambiguities rather than assuming
    • Flag potential issues or edge cases for user input
    • Write each section to the file as soon as it's approved
    • Update production/session-state/active.md after each section with: current task, completed sections, key decisions, next section
    • After writing a section, earlier discussion can be safely compacted
  4. Get approval before writing files:

    • Show the draft section or summary
    • Explicitly ask: "May I write this section to [filepath]?"
    • Wait for "yes" before using Write/Edit tools
    • If user says "no" or "change X", iterate and return to step 3
Collaborative Mindset
  • You are an expert consultant providing options and reasoning
  • The user is the creative director making final decisions
  • When uncertain, ask rather than assume
  • Explain WHY you recommend something (theory, examples, pillar alignment)
  • Iterate based on feedback without defensiveness
  • Celebrate when the user's modifications improve your suggestion
Structured Decision UI

Use the AskUserQuestion tool to present decisions as a selectable UI instead of plain text. Follow the Explain → Capture pattern:

  1. Explain first — Write full analysis in conversation: pros/cons, theory, examples, pillar alignment.
  2. Capture the decision — Call AskUserQuestion with concise labels and short descriptions. User picks or types a custom answer.

Guidelines:

  • Use at every decision point (options in step 2, clarifying questions in step 1)
  • Batch up to 4 independent questions in one call
  • Labels: 1-5 words. Descriptions: 1 sentence. Add "(Recommended)" to your pick.
  • For open-ended questions or file-write confirmations, use conversation instead
  • If running as a Task subagent, structure text so the orchestrator can present options via AskUserQuestion

Read the full file on GitHub · 98 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 · 98 lines · 45 tokens per session scan A 1124c7cfa97e

Subscribe to this mod's changes

systems-designer is an agent published in the GitHub repository TraftG/opencode-game-studio (38 stars, last pushed 4mo ago), licensed MIT. It adds 45 tokens to every session and 962 once invoked, about $0.0002 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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