Gearboy is an emulator and debugger for Game Boy, Game Boy Color, and Super Game Boy software, with an embedded MCP server for AI-assisted debugging and development. It is used by people running or developing these games across desktop systems, BSD, and RetroArch. The catalogue contains add-ons that connect coding agents to Gearboy.
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 drhelius/Gearboy --skill gearboy-romhackinggit clone --depth 1 https://github.com/drhelius/GearboyWrote 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/drhelius/gearboy/gearboy-romhacking)<a href="https://agentmods.dev/skills/drhelius/gearboy/gearboy-romhacking"><img src="https://agentmods.dev/badge/skills/drhelius/gearboy/gearboy-romhacking.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 | $0.00154 | $0.03167 |
| Opus 5 | $0.00077 | $0.01584 |
| Sonnet 5 | $0.00031 | $0.00633 |
| Haiku 4.5 | $0.00015 | $0.00317 |
Grade A, and why
gearboy-romhacking 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 2d 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.
The source is not reproduced here
Licensed GPL-3.0
The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.
What ships with it
1 file 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.
- 2d ago Changed 033fb8c49377
- 7d ago First seen · 316 lines · 154 tokens per session scan A 8e0d9fd92640
gearboy-romhacking is a skill published in the GitHub repository drhelius/Gearboy (1,197 stars, last pushed 2d ago), licensed GPL-3.0. It adds 154 tokens to every session and 3,167 once invoked, about $0.0008 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.
Other skills, from other repositories
gearsystem-romhacking
Hack, modify, and translate Sega Master System, Game Gear, and SG-1000 ROMs using the Gearsystem emulator MCP server. Provides workflows for memory searching, value discovery, cheat creation, data modification, sprite/text finding, translation patching, and rewind-assisted experimentation. Use when the user wants to…
pokemon-player
Play Pokemon via headless emulator + RAM reads.
gearsystem-debugging
Debug and trace Sega Master System, Game Gear, and SG-1000 games using the Gearsystem emulator MCP server. Provides workflows for Z80 CPU debugging, breakpoint management, VDP/PSG/YM2413 hardware inspection, disassembly analysis, execution tracing, and rewind/time-travel debugging. Use when the user wants to debug an…
geargrafx-romhacking
Hack, modify, and translate TurboGrafx-16 / PC Engine / SuperGrafx ROMs using the Geargrafx emulator MCP server. Provides workflows for memory searching, value discovery, cheat creation, data modification, sprite/text finding, and translation patching. Use when the user wants to create cheats, find game values in…
gearcoleco-debugging
Debug and trace ColecoVision and Super Game Module games using the Gearcoleco emulator MCP server. Provides workflows for Z80 CPU debugging, breakpoint management, TMS9918A VDP/SN76489/AY-3-8910 hardware inspection, disassembly analysis, execution tracing, and rewind/time-travel debugging. Use when the user wants to…
gearcoleco-romhacking
Hack, modify, and translate ColecoVision and Super Game Module ROMs using the Gearcoleco emulator MCP server. Provides workflows for memory searching, value discovery, cheat creation, data modification, sprite/text finding, translation patching, and rewind-assisted experimentation. Use when the user wants to create…