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.
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 agentmods add skills/vudovn/ag-kit/game-designnpx skills add vudovn/ag-kit --skill game-designgit 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.svg" alt="Measured on agentmods" 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 | $0.00018 | $0.00639 |
| Opus 5 | $0.00009 | $0.00319 |
| Sonnet 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 6d 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, 1 lines differ
- game-design — 98% identical, 3 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.
- 6d 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 (8,170 stars, last pushed 6d ago), licensed MIT. It adds 18 tokens to every session and 639 once invoked, about $0.0001 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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