Fallout New Vegas AI NPC Mod: Mojave Dialogue and Voice Commands

Yes, you can add AI NPCs to Fallout: New Vegas on PC: a small xNVSE plugin sends the player's words and game events to a Neocortex character, then shows the reply in game and plays it as voice. New Vegas is remembered for its writing, and players still wish they could ask its characters one more question. A Fallout New Vegas AI NPC mod built on Neocortex lets Mojave NPCs answer in their own words, adds voice commands for companions and puts an original trivia host on the Strip. Here is the toolset first, then a worked example in Goodsprings.

Screenshot: Fallout: New Vegas © Bethesda Softworks

New Vegas modding tools at a glance

How the plugin and GECK scripts split the work

New Vegas is a 32-bit game, so your native plugin is a 32-bit C++ xNVSE plugin. It makes HTTPS calls with WinHTTP or libcurl on a worker thread and exposes new script functions your GECK scripts can call.

GECK scripts decide when an NPC speaks, show the reply with the game's message functions, set quest stages and drive companions. For generated voice, the plugin plays the audio returned by the API through its own playback code.

On the Neocortex side, four endpoints cover the whole mod. Dialogue goes through /v3/chat, with the character's actions in the reply. Voice comes from /v3/audio/generate or /v3/audio/stream. Conversation Flows steer branching scenes and return checkpoint keywords (flowState) your GECK quest scripts react to. The quiz engine runs question-and-answer games through /v3/quiz.

Example: a Goodsprings shopkeeper who knows your reputation

Start small, with a handful of characters in Goodsprings or Novac: a prospector, a caravan guard, a shopkeeper who has seen too many couriers come through.

Each becomes a Neocortex character with a Personality type, an Emotion profile and a Knowledge base built from a TXT file about local factions, recent raids and who owes whom. You design them in the node editor, with the Voice and the Actions your scripts handle, and test them in the browser for free.

Your mod sends the player's line with recent events ("the player is wearing NCR armor", "the player's reputation with the Powder Gangers is low") and nearby objects such as the shop counter or a locked gate. Here is how the plugin could build that /v3/chat request:

// xNVSE plugin. HttpPost() is your own WinHTTP wrapper that adds the
// "x-api-key" header from the player's config file. Call it off the game thread.
using json = nlohmann::json;
json body = {
    {"characterIds", json::array({cfg.shopkeeperId})},
    {"message", playerLine},
    {"playerId", "player-1"},
    {"sessionId", sessionId},
    {"metadata", json::array({ {{"id", "gate_01"}, {"name", "Town gate"}},
                               {{"id", "counter_01"}, {"name", "Shop counter"}} })},
    {"events", json::array({ {{"priority", 1}, {"content", "Player wears NCR armor"}} })}};
std::string raw = HttpPost("https://api.neocortex.link/v3/chat", body.dump());

The character answers in voice, each line carries an emotion tag like ANGRY or HAPPY, and actions like OPEN_SHOP or { "name": "OPEN_DOOR", "targetId": "gate_01" } tell your mod what to do.

Faction reputation is what makes this work so well in New Vegas. Send it with each message, and the same shopkeeper is friendly to one player and cold to the next.

Screenshot: Fallout: New Vegas © Bethesda Softworks

Companion orders without the wheel

The companion wheel works, but it breaks the flow of a firefight. Design a command set with actors ("Boone", "ED-E", "everyone"), actions ("wait", "follow", "attack", "use") and objects ("here", "that ghoul", "ranged weapons"). Players say "wait here and keep your distance" or "everyone switch to ranged and attack that ghoul", and your mod receives clean commands, including several actions in one sentence.

It works push-to-talk or always-listening, offline, in multiple languages, using the Neocortex Voice Commands library on the player's machine, without a cloud round trip. See our post on on-device voice commands for game mods for the details. Voice Commands is a licensed SDK: contact us for a Voice Commands license.

Trivia night with Dixie Laroux

Add a new lounge to the Strip with an original host: Dixie Laroux, a silver-voiced emcee who runs trivia between card games. Questions cover pre-war Vegas, the Mojave's factions and the wasteland's odder corners. The question set lives in the Neocortex dashboard and the quiz engine (Team plan) handles questions, scoring and a leaderboard. Your mod pays out chips for a winning streak, and a Conversation Flow can steer Dixie's banter between rounds, returning checkpoint keywords when the player wins the jackpot round.

Set up a Fallout New Vegas AI NPC mod in six steps

1. Install the framework. Set up xNVSE and JIP LN NVSE, then grab the GECK and the GECK Wiki.
2. Design the character in the Neocortex node editor and test it in the browser.
3. Add the extras: a quiz question set for the Strip host, a Conversation Flow for a side story, or a companion command set.
4. Write a small xNVSE plugin that calls the API and exposes functions to your GECK scripts.
5. Keep the API key in a config file each player fills in. Never ship your key inside a shared mod.
6. Test in single-player on a separate save, with your usual stability mods installed.

Fair play in the Mojave

New Vegas is single-player, so an AI NPC mod only changes the player's own Mojave. Keep your mod free and non-commercial, follow Bethesda's terms for player-made content, and use original characters for new content, as with the trivia host above. Use a designed voice or one you own the rights to, and have each player use their own Neocortex API key.

Our recommendation: build the Goodsprings shopkeeper first. One Neocortex character, one request with reputation and nearby objects, and you will quickly see whether the Mojave feels different when it can talk back.

New to voice control in mods? Start with on-device voice commands for game mods, then compare with our Fallout 4 AI NPC mod guide or browse the full AI NPC and voice command mods index.

Tool versions and links checked October 2026. Modding tools change often; check each project's page for the latest release.

Frequently Asked Questions