sega-genesis-sgdk

An agent skill by haroldo-ok, from haroldo-ok/sega-genesis-sgdk-skill-for-claude. Tags: audio, debugging, game-development, graphics, optimization, testing.

What it does

Create, debug, optimize, and port games for the Sega Genesis / Mega Drive in C using SGDK (the Sega Genesis Development Kit). Use whenever the user wants to make a Genesis / Mega Drive game, port an existing game (from DOS, C, a Palm/6502/Java codebase, or any platform) to the Genesis, build or debug an SGDK project, fix a ROM that boots to a black screen or crashes, wire up graphics/sprites/tilemaps/scrolling, convert assets (tiles, sprite sheets, VGM/XGM music, S3M/MOD tracks, WAV samples) with rescomp, set up XGM/XGM2 sound, or add host + headless-emulator tests. Trigger even when the user only says "make a Genesis game", "port X to the Mega Drive", "compile this .res", or "my SGDK build is black screen", or mentions SGDK, rescomp, makefile.gen, VDP_, SPR_, XGM2_, SYS_doVBlankProcess, out/rom.bin, or the m68k-elf / Motorola 68000 toolchain. Prefer this skill over general knowledge for anything touching SGDK: the toolchain, resource format, and API names are easy to get wrong from memory.

Install

With the skills CLI, which installs into Claude Code, Codex, Cursor and other agents:

npx skills add haroldo-ok/sega-genesis-sgdk-skill-for-claude --skill sega-genesis-sgdk

Or copy the skill folder into Claude Code's skills directory by hand (~/.claude/skills for every project, or .claude/skills inside one):

git clone --depth 1 https://github.com/haroldo-ok/sega-genesis-sgdk-skill-for-claude
cp -r sega-genesis-sgdk-skill-for-claude/skills/sega-genesis-sgdk ~/.claude/skills/sega-genesis-sgdk

Safety box score

Grade C, moderate risk: 39 of 100 risk points, rated 2026-10-16. The grade rates what the skill and its scripts can reach on the machine of whoever installs it, across eight categories from shell execution to secrets access. How the score works.

This skill is a local SGDK build-and-test workflow for making Sega Genesis ROMs, but it also installs toolchains, clones/builds third-party emulator code, and touches system paths like `/opt/bin` and `GDK=/opt/sgdk`. The main risks are system-wide package installation, unpinned network fetches, and executing downloaded native code during the headless test path; it does not touch secrets or do remote posting/deploying.

Category levels, from 0 (none) to 3 (high)
Category	Level	Why
Code & shell execution	2 (moderate)	It runs shell commands, compilers, Java, Docker, Python, and a dlopened libretro core (`make -C ...`, `cc ...`, `dlopen`, `r_run()`), so it can execute native code during setup and testing.
Network access	2 (moderate)	It fetches external code and packages (`git clone --depth 1 https://github.com/ekeeke/Genesis-Plus-GX.git`, `docker pull doragasu/sgdk`, `apt-get update/install`), so install/test pulls from the network.
Filesystem reach	2 (moderate)	It writes outside the project with `/opt/bin` symlinks and expects `GDK=/opt/sgdk`, while `make clean` removes build output under `out/`; the blast radius includes system paths.
Secrets & credentials	0 (none)	No file reads or prompts for tokens, keys, `.env`, browser sessions, or other credentials.
Privilege & persistence	2 (moderate)	The apt route explicitly uses `sudo apt-get update`/`sudo apt-get install` and creates symlinks in `/opt/bin`, so it may require admin rights and system-wide changes.
Instruction hijack surface	0 (none)	I found no prompt-injection text that tells the agent to ignore instructions, hide actions, or follow fetched prompts.
Irreversible actions	0 (none)	It automates local build/test only; there is no posting, purchasing, deploying, or deleting outside the workspace.
Transparency	2 (moderate)	Several dependencies are fetched live and unpinned (`docker pull doragasu/sgdk`, `git clone --depth 1 ...Genesis-Plus-GX.git`, `git clone --depth 1 ...marsdev.git`), so reviewers cannot inspect the exact code or image that will run.

Before installing

Read `assets/setup.sh` and decide whether you accept `sudo apt-get` plus `/opt/bin` changes on this machine.
If you will use tier-2 testing, pin or vendor `Genesis-Plus-GX` instead of cloning it live.
Run the skill first in a disposable VM/container with a throwaway `GDK` tree and verify `out/rom.bin` is the only project output you care about.

Rated 2026-10-16 by an automated review of 19 files from the skill's repository.

Source

Repository: haroldo-ok/sega-genesis-sgdk-skill-for-claude (all skills from this repository)
Path: skills/sega-genesis-sgdk/SKILL.md
Branch: main
Updated: 2026-09-23

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