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.
npx skills add xonovex/platform --skill c99-game-opinionated-guidegit clone --depth 1 https://github.com/xonovex/platformWrote 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/xonovex/platform/c99-game-opinionated-guide)<a href="https://agentmods.dev/skills/xonovex/platform/c99-game-opinionated-guide"><img src="https://agentmods.dev/badge/skills/xonovex/platform/c99-game-opinionated-guide/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/xonovex/platform/c99-game-opinionated-guide"><img src="https://agentmods.dev/badge/skills/xonovex/platform/c99-game-opinionated-guide.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 | $0.00112 | $0.00834 |
| Opus 5.5 | $0.00045 | $0.00334 |
| Sonnet 5.5 | $0.00022 | $0.00167 |
| Haiku 4.5 | $0.00011 | $0.00083 |
Grade A, and why
c99-game-opinionated-guide 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 17d 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 — 49 lines — stays where its author put it; the contents beside it link to each section on GitHub.
C99 Game Engine Opinionated Guidelines
Build C99 game runtimes with caller-owned memory, contiguous data, and explicit engine boundaries. Apply c99-guide for the shared C99 foundation.
Requirements
- Overlay on c99-guide - This guide carries only the game/engine opinionated decisions; for generic C99 idioms:
const-correctness, designated initializers (ZII), fixed-width types, value-oriented APIs, and baseline error/return patterns, follow c99-guide
Math
- Types - 16-byte aligned vectors/matrices/quaternions, see references/math-types.md
- Access - Use accessor functions for matrices, direct fields for vectors, see references/math-types.md
- Coordinates - Right-handed Y-up, CCW winding, configurable clip depth, see references/coordinate-system.md
- Suffixes -
_aos/_soalayouts,_simdeSIMD,2d/3ddimensions
Geometry Pipeline
- Analytic → Discrete → Packing - Separate logic/rendering/GPU layers, see references/geometry-pipeline.md
- Builder pattern -
*_req()query size,*_build()write to caller buffer, see references/builder-pattern.md
Patterns
- Inverse mass - Store
1/mass, static objects use0.0, see references/physics-patterns.md - SoA optimization - AoS for single objects, SoA for batches, see references/mesh-types.md
- Validation - Check capacity, bounds, NULL, overflow before operations
Gotchas
- Vertex packing order matters for GPU upload: pack tightly and match the shader's attribute layout, not the C struct's natural padding
- Quaternion math is sensitive to normalization drift: re-normalize after long chains of multiplications
- Tagged unions with a sentinel
TYPE_INVALID = 0save initialization bugs; designated initializers default fields to zero - Builder patterns in C99 work via opaque structs + functions; never expose mutable struct fields across the public boundary
What ships with it
12 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.
- eval-queries.json 4.8 KB
- evals.json 2.2 KB
- moon.yml 166 B
- references/builder-pattern.md 574 B
- references/coordinate-system.md 615 B
- references/geometry-pipeline.md 723 B
- references/math-types.md 412 B
- references/mesh-types.md 667 B
- references/physics-patterns.md 695 B
- references/spatial-structures.md 666 B
- references/vertex-packing.md 974 B
- SOURCES.md 589 B
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.
- 17d ago Changed · +2 lines 01b93f38b1a2
- 1mo ago First seen · 47 lines · 112 tokens per session scan A ad6acad4f290
c99-game-opinionated-guide is a skill published in the GitHub repository xonovex/platform (6 stars, last pushed yesterday), licensed MIT. It adds 112 tokens to every session and 834 once invoked, about $0.0004 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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