Lexis-AI

Creating a System Pack

A system pack teaches Lexis-AI one game’s rules. The commands never name a system; they read the pack’s files by role. Adding a system means adding one folder under plugin/systems/ and nothing else: lexis-setup lists it in the game system menu automatically.

The full design is in design/system-packs.md.

1. Check the license first

A pack may only contain rules you are allowed to restate:

• Open licenses (CC-BY, ORC, OGL 1.0a, a publisher’s third-party license that allows it): fine, with the required attribution or notice.
• Closed rules (no open license, or a non-commercial fan license only): no pack.

Read the license on the publisher’s own page and note exactly what it requires (attribution text, notices, share-alike, trademark limits).

2. Content rule: mechanics only

Allowed: how rolls work, difficulty scales, outcome bands, character math (scores, modifiers, hit points, derived values, advancement), generic conditions and harm, generic GM procedures, setting-free examples you wrote yourself, the required license text.

Never:

• setting content: worlds, places, gods, factions, history, named characters or creatures, adventures, story;
• spell, power, item or monster lists copied wholesale; art; layout;
• trademarks as names. Name the pack after its mechanics (srd5, d100, fitd); use a brand only where its owner allows it, never as a claim of endorsement;
• rule text from games that are not open-licensed.

Write the rules in your own short words, even when the license would allow copying. A pack is a GM’s cheat sheet, not a copy of the rulebook.

3. The files

plugin/systems/<id>/
  pack.md              # identity, license, content scope, glossary, seam, never
  resolution.md        # how a roll works + the answer shape for /help-skills
  scene-tags.md        # what a scene tag is in this system + its output block
  obstacles.md         # difficulty, opposition, hazards, costs + the obstacle output block
  entities.md          # system sections of character, location and group files; character math
  init-questions.md    # the system's questions for /world-init
  templates/system.md  # the world's system.md for this system

No other files are allowed in a pack folder.

pack.md

---
type: system-pack
id: <id, same as the folder name>
name: <menu name>
order: <position in the install menu>
version: 0.1.0
---

# System Pack: <name>
<what it is, when to use it>

## License
<attribution / notices exactly as the license requires>

## Content scope
Mechanics only … No setting content …

## Glossary
| Role | Term in this system |
|---|---|
| check | … |
| trait | … |
| difficulty | … |
| scene-tag | … |
| special-ability | … |
| harm | … |
| meta-currency | … |

## Files
## Seam (core → pack)
## Never

Every glossary role must have a row (write — if the system has nothing for it).

resolution.md

How a roll works, the difficulty scale, what results mean, the traits (skills, abilities, approaches, actions) and a section ## Answer shape for /help-skills with the steps and a fenced output example.

scene-tags.md

What a scene tag is in this system (an aspect, a scene feature, a modifier, a clock …), the kinds with their rule effects, and an output block with Effect, Use it and Against them lines.

obstacles.md

How to suggest a difficulty, passive vs active opposition, obstacle types (barrier, puzzle, hazard or trap, social, multi-step), a cost menu, and an output block that starts with a bold system label (e.g. **5E**).

entities.md

Which sections replace the `` line in the character, location and group templates (NPC and PC separately), a one-line NPC stat line, and the character math.

init-questions.md and templates/system.md

5-6 optional setup questions (unanswered = standard), and the matching system.md with a ## Homebrew and a ## Uncertain section. The template’s frontmatter has system: <id>.

4. Test it

cd lexis-setup
go test ./...

TestSystemPacksContract checks every pack:

• exactly the seven contract files, nothing else;
• pack.md has id (= folder name), name, the ## License, ## Content scope, ## Glossary and ## Never sections, and a glossary row for every role;
• templates/system.md names the pack;
• no file contains a term from the setting/brand denylist (outside ## License). Add the setting names of your source system to the denylist in lexis-setup/packs_test.go.

Then install only your pack into a test folder and try it:

go run . --source ../plugin --platform claude --scope project --dir /tmp/test-world --lang English --system <id> --yes

Run /world-init, /help-skills, /create-aspect and /create-obstacle with the same scene you used for another system, and compare: the fiction part should match, the mechanics in your system’s terms.

5. Document it

Add the pack to the table in Game systems, to the --system list in Installation and the README, and to the pack table in design/system-packs.md.