Realtime Voice APIs for Game NPCs - 2026 Comparison
ComparisonAI VoiceLLMs
Real-time voice models are good enough now that a talking NPC demo takes an afternoon. Choosing which API to build on is harder, and most of them were designed for customer service, not games.
Here is how the main voice APIs compare for game characters as of October 2026.
Quick comparison
| API | Status | Unity support | Pricing basis | Session limits | Notes |
|---|---|---|---|---|---|
| OpenAI Realtime | Active | No official SDK | Audio and text tokens | 60 minutes | Strong models, WebRTC or WebSocket |
| Gemini Live | Active | Firebase AI Logic preview, older models only | Audio and text tokens | Around 10-minute connections, resumable | Low raw cost |
| ElevenLabs Agents | Active | No SDK | Per minute plus LLM | Plan-based concurrency | Best-in-class voices |
| Deepgram Voice Agent | Active | No package, C# SDK | Per minute of connection | Plan-based concurrency | Mix-and-match providers |
| Amazon Nova Sonic | Active | No | Tokens | 8-minute connections, 20 sessions per region | Contact-centre focus |
| Hume EVI | Shutting down November 13, 2026 | No | Not published | 30 minutes | Migrate now |
What every voice API leaves to you
None of these APIs is a game character. With any of them, you still build:
- A Unity or engine audio client, including WebGL where Unity has no microphone support.
- A backend that issues short-lived tokens, so secret keys never ship in your game.
- The character: personality, knowledge, memory and guardrails as prompts.
- Session handling: reconnecting before time limits and keeping context.
- Game integration: turning function calls into actions and feeding scene state back.
- Cost control for per-minute or per-token billing.
- Maintenance as models, prices and APIs change, or shut down.
The platform alternative
Neocortex sits one level up. Instead of a voice API, you get the whole character: designed in a visual editor, voiced with a cloned or designed voice, and delivered through SDKs for Unity, Unreal and Godot (beta), or the Web API.
| Voice API | Neocortex | |
|---|---|---|
| Engine SDK | Usually build your own | Unity, Unreal, Godot (beta) |
| WebGL microphone | Build your own | Included |
| Character design | Prompts | Visual node editor |
| Voices | Provider presets | Voice cloning and voice design |
| Game actions | Wire up function calls | Actions and interactables built in |
| Vendor changes | Your problem | Our problem |
How to choose
- Building your own voice platform and want raw control: OpenAI Realtime or Gemini Live.
- Voice quality above all, outside an engine: ElevenLabs Agents.
- Characters in a game, shipped soon: Neocortex.
Individual comparisons
- OpenAI Realtime API vs Neocortex
- Gemini Live API vs Neocortex
- ElevenLabs Agents for game NPCs
- Deepgram Voice Agent vs Neocortex
- Amazon Nova Sonic vs Neocortex
- Hume EVI is shutting down
API details were last checked in October 2026.
Written by
Sercan Altundas
Date
Oct 17, 2026
Read time
6 min
