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Modder2 min read

Building with AI coding agents

Much of this scene was built with Claude Code, Codex and friends. How people use them for modding, and how not to get burned.

A lot of the projects here say openly that an AI coding agent wrote most of the code. ArkWeb even asks you to let Claude set the mod up on your PC. Agents are good at the tedious parts (reading decompiled code, writing both halves of a bridge, writing test harnesses, iterating on a crash for hours) but they need direction.

What works

  • Give it the design up front. Point the agent at SkyCraft's DESIGN.md or universal-modder's mashup-mods playbook before it writes a line. Agents copy patterns well; give them a good pattern.
  • Keep a progress log in the repo. A PLAN.md or DEVLOG.md with "done / next / known bugs" lets each new session pick up where the last stopped. SubCraft's MISSION.md and DEVLOG.md are good examples.
  • Make it test without the games. Ask for a fake stand-in for each game (a small script that writes the same shared memory), so the link can be tested in seconds instead of launching two games each time.
  • Small steps, verified in-game. Camera sync, then collision, then drawing. Run the game yourself after each step; agents are confident about things they haven't seen.
  • Logs over guesses. Have it add logging everywhere, then paste real log output back.
  • Toolkits help. universal-modder packages skills for recon, reverse engineering, asset generation and in-game testing.

What to watch out for

  • Read before you run. Anything that injects into a process or downloads and runs files deserves a look before you execute it, especially code you didn't ask for.
  • Don't let it "fix" security. If an agent suggests disabling antivirus, Windows protections or a game's anti-cheat for an online game, say no.
  • Licences. Agents happily paste code from elsewhere. Keep upstream licence notices (MIT, Apache, GPL) and credit the projects you build on.
  • No game files in the repo. Check what gets committed. Extracted assets, executables and ROM dumps must never go into git.
  • Honest READMEs. Say what works, what doesn't, and which versions you tested. Nothing frustrates players more than a README written by an optimistic agent.

Letting players use an agent to install

ArkWeb's approach (an AGENTS.md that tells the player's agent how to check versions, build, install, back up saves and coach a first session) is a neat answer to "this is too hard to install". If you do this, keep the steps explicit and safe: back up first, ask before changing anything, and never touch online modes.