Borrowing it
Nothing to install: this file belongs to nicepkg/agent-world. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/nicepkg/agent-world/main/.claude/skills/game-design-theory/SKILL.mdgit clone --depth 1 https://github.com/nicepkg/agent-worldWrote 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/skills/nicepkg/agent-world/game-design-theory)<a href="https://agentmods.dev/skills/nicepkg/agent-world/game-design-theory"><img src="https://agentmods.dev/badge/skills/nicepkg/agent-world/game-design-theory/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/skills/nicepkg/agent-world/game-design-theory"><img src="https://agentmods.dev/badge/skills/nicepkg/agent-world/game-design-theory.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 | $0.00031 | $0.01512 |
| Opus 5.5 | $0.00012 | $0.00605 |
| Sonnet 5.5 | $0.00006 | $0.00302 |
| Haiku 4.5 | $0.00003 | $0.00151 |
Grade A, and why
game-design-theory 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 2mo 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.
How it starts
The opening of the file, as written. The whole thing — 213 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Game Design Theory
The MDA Framework
┌─────────────────────────────────────────────────────────────┐
│ MDA FRAMEWORK │
├─────────────────────────────────────────────────────────────┤
│ MECHANICS (Rules): │
│ → Player actions, constraints, state changes │
│ → Example: Jump has height limit, costs stamina │
│ ↓ │
│ DYNAMICS (Behavior): │
│ → Emergent gameplay from mechanic interactions │
│ → Example: Wall-jump combos, speedrun routes │
│ ↓ │
│ AESTHETICS (Experience): │
│ → Emotional responses: Fun, tension, achievement │
│ → Example: Flow state, satisfaction, immersion │
└─────────────────────────────────────────────────────────────┘
Core Game Loop
┌─────────────────────────────────────────────────────────────┐
│ ENGAGEMENT LOOP │
├─────────────────────────────────────────────────────────────┤
│ 1. INPUT → Player takes action │
│ 2. PROCESS → Game calculates results │
│ 3. FEEDBACK → Immediate visual/audio response │
│ 4. REWARD → Progress, points, unlocks │
│ 5. REPEAT → Loop invites next iteration │
│ │
│ Loop Quality Criteria: │
│ ✓ Fast feedback (< 100ms) │
│ ✓ Clear causation │
│ ✓ Rewarding outcomes │
│ ✓ Compelling repetition │
└─────────────────────────────────────────────────────────────┘
What ships with it
3 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.
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.
- 2mo ago First seen · 213 lines · 31 tokens per session scan A 548e01881f65
game-design-theory is a skill published in the GitHub repository nicepkg/agent-world (6 stars, last pushed 8mo ago), licensed MIT. It adds 31 tokens to every session and 1,512 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-08-31.
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