AG Kit is a toolkit that gives Google Antigravity coding agents a structured workspace with rules, skills, specialist agents, workflows, persistent memory, orchestration, MCP guidance, and a safety hook. It is for building and operating agent workflows in Antigravity, and its catalogue entries provide parts of that workspace contract.
Borrowing it
Nothing to install: this file belongs to vudovn/ag-kit. 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/vudovn/ag-kit/main/.agents/skills/game-development/game-design/SKILL.mdgit clone --depth 1 https://github.com/vudovn/ag-kitWrote 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/vudovn/ag-kit/game-design)<a href="https://agentmods.dev/skills/vudovn/ag-kit/game-design"><img src="https://agentmods.dev/badge/skills/vudovn/ag-kit/game-design/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/vudovn/ag-kit/game-design"><img src="https://agentmods.dev/badge/skills/vudovn/ag-kit/game-design.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00018 | $0.00639 |
| Opus 5.5 | $0.00007 | $0.00256 |
| Sonnet 5.5 | $0.00004 | $0.00128 |
| Haiku 4.5 | $0.00002 | $0.00064 |
Grade A, and why
game-design 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.
Copies of this mod
8 near-identical copies found in the catalogue:
- game-design — 100% identical, 0 lines differ
- game-design — 100% identical, 0 lines differ
- game-design — 100% identical, 0 lines differ
- game-design — 100% identical, 0 lines differ
- game-design — 100% identical, 0 lines differ
- game-design — 98% identical, 3 lines differ
- game-design — 98% identical, 1 lines differ
- game-design — 86% identical, 14 lines differ
How it starts
The opening of the file, as written. The whole thing — 130 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Game Design Principles
Design thinking for engaging games.
1. Core Loop Design
The 30-Second Test
Every game needs a fun 30-second loop:
1. ACTION → Player does something
2. FEEDBACK → Game responds
3. REWARD → Player feels good
4. REPEAT
Loop Examples
| Genre | Core Loop |
|---|---|
| Platformer | Run → Jump → Land → Collect |
| Shooter | Aim → Shoot → Kill → Loot |
| Puzzle | Observe → Think → Solve → Advance |
| RPG | Explore → Fight → Level → Gear |
2. Game Design Document (GDD)
Essential Sections
| Section | Content |
|---|---|
| Pitch | One-sentence description |
| Core Loop | 30-second gameplay |
| Mechanics | How systems work |
| Progression | How player advances |
| Art Style | Visual direction |
| Audio | Sound direction |
Principles
- Keep it living (update regularly)
- Visuals help communicate
- Less is more (start small)
3. Player Psychology
Motivation Types
| Type | Driven By |
|---|---|
| Achiever | Goals, completion |
| Explorer | Discovery, secrets |
| Socializer | Interaction, community |
| Killer | Competition, dominance |
Reward Schedules
| Schedule | Effect | Use |
|---|---|---|
| Fixed | Predictable | Milestone rewards |
| Variable | Addictive | Loot drops |
| Ratio | Effort-based | Grind games |
4. Difficulty Balancing
Flow State
Too Hard → Frustration → Quit
Too Easy → Boredom → Quit
Just Right → Flow → Engagement
Balancing Strategies
| Strategy | How |
|---|---|
| Dynamic | Adjust to player skill |
| Selection | Let player choose |
| Accessibility | Options for all |
5. Progression Design
Progression Types
| Type | Example |
|---|---|
| Skill | Player gets better |
| Power | Character gets stronger |
| Content | New areas unlock |
| Story | Narrative advances |
Pacing Principles
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 · 130 lines · 18 tokens per session scan A 93c417904682
game-design is a skill published in the GitHub repository vudovn/ag-kit (8,199 stars, last pushed 3d ago), licensed MIT. It adds 18 tokens to every session and 639 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 2026-08-30.
Other skills, from other repositories
playtest-report
Structured playtest report template, or turn existing playtest notes into structured feedback.
godot-signals-groups
Build event-driven, decoupled Godot 4.7 gameplay with signals and node groups: declare and emit custom signals, connect with Callables (incl. bind/one-shot), and broadcast to many nodes via groups and callgroup. Use when wiring node communication in a Godot project, replacing tight references with signals…
motion
Reconstruct a skeleton from calibrated mesh projections and sequential VLM joint annotations, then fit joints and skin weights. Generate motion from joint-position trajectories, rhythm and contact constraints through IK; refine bone orientation against the action, then export, retarget and validate on the target mesh.
unity-addressables
Manage Addressables groups, entries, profiles and content builds (com.unity.addressables, reflection-based).
unity-manual-component
Manually add, configure, reorder, and copy components on GameObjects using Unity Editor UI. For one-off Inspector workflows that do not need REST automation.
threejs-exposure-color-grading
Build a measured exposure and grading path in Three.js. Use for a 64x36 encoded luminance meter, asynchronous readback, weighted log-average exposure, asymmetric adaptation, single tone-map ownership, and a generated 32-cube post-tone-map LUT.