What is Sylvia GM?

After installing the app, open Settings → Packages and install the included SRD Lite package.

1 Connect a model

Open Settings → Models → Add model.

Choose how Sylvia will reach the AI: a supported account connection, an API service or a local model server. Connect the service, select a model and save it.

Sylvia fills in known settings where it can. If a necessary setting is missing, it asks for that value. You can choose a default for new chats, while existing chats keep their own model selection.

A hosted service may charge for usage or apply subscription limits. A local model server needs to be running already; Sylvia doesn’t install or start it for you. Model quality and tool support affect how well the GM and Builder work.

A ChatGPT account connection requires the supported Codex runtime to be installed separately. A listed connection option does not guarantee support for every account or model. Use the release notes for setup instructions and the connections verified for this build.

2 Choose what you want to play

Start a New Campaign and work through the Campaign Interview.

The setup brings together three pieces:

• Ruleset: how the game works, including supported actions, dice, resources and character requirements
• Campaign Setting: the world, its people and the rules used there
• Campaign Plan: the adventure Sylvia will run, including its situations, important events and private GM material

Choose compatible content at each step. The Plan chooser lets you browse and search adventures, read their public descriptions and check their starting-character requirements without opening the GM’s secrets.

3 Set up your character and party

Use the starting characters allowed by the adventure, select compatible saved characters or open Builder to make a player character or companion.

Builder opens as its own saved conversation. You can leave it and return later. When completed content is available, return to campaign setup and choose what you want to use.

Some adventures have a fixed protagonist or other party requirements. Those choices come from the selected adventure.

4 Start playing

Finish the setup and begin the campaign. Sylvia introduces the situation and waits for your input.

Most play happens through conversation. You can say what your character does, speak to someone in the scene or ask about what you can see.

For example, you might write:

“I ask the guard who came through the gate last night, then look for another way into the courtyard.”

That is an example of player input. The response depends on the campaign, its current state and the selected rules.

Sylvia reads the relevant campaign material and considers your attempt. If a supported rule applies, she asks the game engine to resolve it.

The engine checks the game state, applies the rules and records the result. Sylvia then uses that result to describe what happened.

During play, result cards and the ruleset’s game panels let you inspect mechanical outcomes and current character information. The precise information depends on the ruleset. In SRD play, that includes things such as checks, hit points, resources and combat results.

The model still makes GM decisions about the fiction. Encoded rules provide the mechanical boundaries for those decisions. You can inspect mechanical results and saved campaign information during play. AI narration can still be mistaken; include disagreements between the narration, displayed result and saved state when reporting a problem.

SRD Lite combat uses positions on a map for movement, range, targeting and area effects. Those positions belong to the game state, so the same position information is used by the relevant combat rules.

Outside combat, you can explore and roleplay through conversation without moving your character around the map for every action.

A campaign keeps its conversation and saved state so you can leave and reopen it later.

The Campaign Plan gives Sylvia prepared situations, objectives, private facts and conditions for moving the story forward. Your actions determine what actually happens during play. The saved record carries those outcomes into later scenes.

Campaigns can also be exported for recovery or transfer. Provider credentials are kept separate from campaign exports.

Open a Builder session when you want to make or revise game content. You can describe a world, an adventure, a character or a set of rules in ordinary language.

Builder uses Sylvia’s content definitions and reference material to work on the files. It can ask questions, show what needs fixing and revise the draft.

The normal workflow is:

• Describe what you want to create
• Answer the necessary questions and review the result
• Have Builder validate the content and correct reported problems
• Save the completed content to your local library
• Select it in a compatible campaign

Ruleset authoring also supports saved test scenarios. Builder can run them, inspect failures and correct the draft. These tests check the authored scenarios and relevant game-loop behaviour. Generated content still benefits from your review and play-testing.

You can import supported content packages and use compatible saved material. Imports go through the applicable format and compatibility checks. Arbitrary books or files don’t automatically become a playable ruleset or adventure.

Saving to Sylvia’s local library keeps the content on your computer. It doesn’t publish it to a public marketplace.

The launch focus is:

• Solo campaigns on Windows
• SRD Lite, based on the SRD 5.2.1, with 117 supported spells
• Severed Lands setting and adventures, with 17 Campaign Plans in the launch content set
• A No Ruleset option
• GM and Builder conversations
• Supported hosted-model connections and already-running local model servers
• Saved campaigns and portable content

SRD Lite has a limited launch scope; consumables are outside this release. Custom content and model behaviour still need review and play-testing. Multiplayer, SRD Full, mobile and native macOS or Linux clients are outside this first Alpha. Linux support is in the pipeline. See the release notes for the limitations of the published build.

Sylvia itself is free. Any model-service charges or subscription limits are separate.

Your campaigns and reusable content are stored locally. When you use a hosted model, the material sent for that request goes to your chosen provider, under its terms and privacy policy.

Sylvia's covered software is source-available under PolyForm Noncommercial 1.0.0 with Sylvia Additional Permissions, adopted on 16 October 2026, revision 3. Use restrictions apply. Included content and dependencies retain their applicable licences, and earlier MIT grants remain preserved. Base licence, Additional permissions and Scope and preserved grants describe the actual terms.

Read the development journal: https://pneuma-io.dev/sylvia-gm/blog/

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