NFS Underground 2 and Most Wanted AI Mod: A Talking Crew Chief

Quick answer: an NFS Underground 2 or Most Wanted AI mod is a C++ ASI plugin that reads the race, sends it to an AI character and plays back what that character says. The Black Box era of Need for Speed still has a huge modding scene, with car packs, widescreen fixes, ExtraOptions and entire career overhauls, but neither game has anyone to talk to between races. Neocortex supplies the AI character, its voice, quizzes and on-device voice commands, and your plugin connects them to the game. The result is a crew chief who knows your car, reads the race as it happens and answers back.

Screenshot: Need for Speed: Underground 2 © Electronic Arts

One race, from the crew chief's side

Give the player an original crew chief with a personality: a calm ex-drifter, or a loud tuner who lives in the garage. During the race your plugin collects events: position, gap to the leader, nitrous left, a wall hit on the last corner, a perfect launch.

You finish second. The player asks "How did I do?", and the plugin builds the chat request:

// Build the /v3/chat body when the race ends (g_sessionId starts empty).
std::string body = R"({
  "characterIds": ["CREW_CHIEF_ID"],
  "message": "How did I do?",
  "playerId": "player-1",
  "sessionId": ")" + g_sessionId + R"(",
  "events": [{ "priority": 1, "content": "Finished 2nd, lost 1.3s in the last hairpin, nitrous empty" }]
})";
// POST https://api.neocortex.link/v3/chat on a worker thread (WinHTTP or libcurl)
// Headers: Content-Type: application/json, x-api-key: <key from the plugin's .ini>
// Reply: messages[0].lines[] -> subtitles + emotion, actions[] -> game code, keep sessionId

The answer is about that race, in character, with an emotion tag you can use for tone. Ask "what did I do wrong?" and the chief points at the hairpin. Actions let the chief do more than talk, for example { "name": "SUGGEST_TUNE", "targetId": "gearing" } to open the right tuning screen. Keep the returned sessionId and the next race picks up where this conversation left off.

What else the crew chief can do

With voice commands the player keeps both hands on the wheel or pad. Your plugin receives the matched command and runs it, or hands it to the crew chief for a spoken answer. The command set is designed as actors ("crew chief"), actions ("show", "check", "open") and objects ("nitrous", "map", "garage"), and players can phrase things naturally.

The quiz is built as a question set in the Neocortex dashboard. The quiz engine handles questions, scoring and a leaderboard, and the player answers out loud through speech-to-text. A perfect score could even earn a reward through your own mod logic.

NFS Underground 2 and Most Wanted AI mod toolkit

Both games are 32-bit Direct3D 9 titles, and their modding scene runs on native ASI plugins and data editors:

Data editors change content. Anything that talks, listens or calls the web is a C++ ASI plugin. It runs inside the game, reads race and career state through community-documented memory addresses and hooks, makes HTTPS requests with WinHTTP or libcurl on a worker thread, draws subtitles through a Direct3D 9 hook or an overlay library, and plays voice audio with the Windows audio APIs.

Screenshot: Need for Speed: Underground 2 © Electronic Arts

The Neocortex calls behind it

The plugin reads game state, sends it with the player's line to a Neocortex character (/v3/chat), shows the reply as subtitles, plays the voice from /v3/audio/generate or /v3/audio/stream, and runs the actions the character returns. The quiz engine runs the safehouse trivia through /v3/quiz, including scoring and leaderboard. Voice commands turn spoken phrases into game actions without a cloud round trip: Neocortex Voice Commands runs on the player's machine, push-to-talk or always listening, in multiple languages.

Voice Commands is a licensed SDK: contact us for a Voice Commands license.

Fair play with EA's games

Keep the mod single-player and non-commercial, follow EA's user agreement for the game, and do not redistribute EA's game files: ship only your plugin and its config. Each player uses their own Neocortex API key, and nothing in the mod should give anyone an edge in online play or community leaderboards.

From garage to first race

1. Set up the game with Ultimate ASI Loader and the widescreen fix, and ExtraOptions if you use it.
2. Design your crew chief in the Neocortex visual editor: personality, emotions, knowledge about cars and tuning, voice. Add a quiz or a voice command set. Test it in the browser for free.
3. Create a C++ ASI plugin that reads the race data you need and shows text on screen.
4. Connect to the API from a worker thread and play the returned audio.
5. Read the API key from an .ini file each player fills in with their own key.
6. Test in single-player career and quick races.

Our recommendation: build the post-race debrief first. It needs only a handful of race events and one chat call, and once the crew chief answers "how did I do?" well, voice commands and the quiz are additions to a character that already works. The same ASI approach powers our GTA San Andreas and Vice City AI NPC mod guide. For the voice side, read about on-device voice commands for game mods, or see how Neocortex compares on our comparison page.

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

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