Narrative design
Narrative design is the discipline of shaping how a game tells its story through its systems, structure, and player choices, not only through the words characters say. A game writer authors dialogue and prose; a narrative designer decides how quests branch, how the world reacts to the player, how pacing works, and how story is delivered through mechanics. It is the bridge between a written world and a playable one. Tools in this space range from wikis that organise lore to authoring tools like LoreWeaver Architect that turn lore into data an engine can run.
AI game master (AI GM)
An AI game master is a system that plays the role a human game master plays at a tabletop: it runs the story. It decides what happens next, paces events, adjudicates outcomes, and makes the world react, rather than voicing one character. This is distinct from an AI NPC, which gives a single character a voice. An AI GM operates at the level of the whole experience. LoreWeaver Director is an on-device AI game master, currently in beta, and the distinction is covered in depth in on-device AI game master middleware.
AI NPC
An AI NPC is a non-player character driven by AI, usually a language model, so it can hold a conversation, remember what happened, and react in real time, instead of following a fixed script. AI NPCs are a character-layer technology: they make individual characters feel alive. They are not the same as an AI game master, which orchestrates the world around those characters. Cloud tools such as Convai and Inworld focus on this layer; the trade-offs are compared in Inworld and Convai alternatives.
On-device AI (local inference)
On-device AI means running the AI model on the player's own hardware, their CPU or GPU, rather than sending each request to a cloud server. For games this matters for three reasons: it removes the per-request cloud fee that scales with your player count, it removes the dependency on a live network connection, and it keeps data on the player's machine. The trade is that it uses some of the player's compute. On-device is the opposite of the usage-billed cloud model used by most AI NPC platforms; see LoreWeaver vs Inworld for a concrete comparison.
Constraint-validated narrative
Constraint-validated narrative is an approach where an AI's proposed narrative output is checked against explicit rules before it is accepted. Those rules can encode canon, lore, character facts, and current game state. If a proposed decision would contradict an established fact or break a defined rule, it is rejected or corrected rather than shown to the player. The point is to get the flexibility of a generative model without letting it wander outside your story. It is the mechanism LoreWeaver Director uses to keep AI-driven narrative inside author-defined boundaries.
Emergent narrative
Emergent narrative is story that arises from the interaction of systems and player choices rather than being written out in advance. Instead of a fixed script, the game sets up rules and actors, and the story emerges from how they combine. The long-standing tension is between emergence and coherence: fully emergent systems can produce incoherent or lore-breaking results. Techniques like constraint validation exist to get emergent behaviour that still respects the author's world.
Worldbuilding
Worldbuilding is the craft of constructing a fictional world: its lore, history, geography, factions, characters, and internal rules. For novelists and tabletop GMs the output is usually a browsable reference, which is what wikis like World Anvil are built for. For game developers there is an extra step: turning that world into data the engine can actually use. That gap between a written world and a runnable one is the difference explored in LoreWeaver vs World Anvil.
Engine-ready narrative data (lore-to-data)
Engine-ready narrative data is lore represented as structured, typed data, entities, mapped relationships, and branching logic, in a form a game engine such as Unreal, Unity, or Godot can load and run. It is the opposite of lore that lives as prose in documents, which a person has to read and re-type into the engine by hand. Converting a written world into this form is exactly what LoreWeaver Architect does, exporting to Unreal, Unity, Godot, or JSON.
Branching narrative
Branching narrative is a story structure where player choices lead to different paths, states, and outcomes. Rather than a single linear script, it is represented as a graph of nodes connected by conditions: reach this node with this state, and the story goes one way; reach it another way, and it goes another. Branching is what makes choices feel consequential, and representing it as structured data is part of what turns a written world into something an engine can play.