Case Vault

Landing Page
Gameplay - Investigation Scene
Suspect Interrogation
Evidence Board
Case Files & Truth System

Inspiration

I grew up loving Phoenix Wright and Sherlock Holmes, but the tragedy is: once solved, it's over forever. I wanted a game that never runs out of cases. With Gemini 3's multimodal capabilities, I built an AI "Dungeon Master" that creates coherent, solvable, atmospheric mysteries on demand.

What It Does

Case Vault generates a complete murder mystery from a simple prompt (e.g., "Cyberpunk Tokyo" or "Victorian London"):

Procedural Storytelling: Creates victim, method, hidden truth, and 4 unique suspects
AI Interrogation: You talk to suspects—they remember everything and slip up if caught lying
Dynamic Visuals: Every scene and character visualized instantly
Episodic Progression: 6 episodes unlock new evidence and timeline events

Challenges I Ran Into

Hallucination Control: Solved by generating a rigid JSON "Truth File" first—ground truth for all AI agents
Latency Management: Implemented eager loading and narrative transitions to hide API wait times
Visual Consistency: Tuned prompts with specific noir aesthetic tokens

Accomplishments I'm Proud Of

✅ Win/Lose state in an LLM game—not just a chatbot
✅ Episode System that makes detective work feel earned
✅ 100% client-side with just an API key

🌍 Market Impact

Sector	Application
Gaming	Eliminates content creation costs with infinite procedural mysteries
Education	Teaches logic, reasoning, and evidence analysis through engagement
Accessibility	Browser-based, no install, works on any device

Traction

[x] Functional MVP with 6-episode progressive mystery
[x] 3 difficulty levels with delayed suspect mechanics
[x] Procedural UI sound effects
[ ] Multiplayer mode (in development with Supabase Realtime)

🚀 What's Next

Multiplayer Mode (Priority)

Room System: Share 6-digit code for friends to join
"Good Cop / Bad Cop": 2-4 players interrogate together
Party Difficulty: 7-8 suspects with complex alibis

Future Features

Voice Integration: Speak to suspects via microphone
Persistent Campaigns: Save detective stats across cases
Video Evidence: Veo integration for motion CCTV footage

Built With

css3
google-gemini-api
html5
javascript
vite

Submitted to

Gemini 3 Hackathon

Created by

I built Case Vault entirely as a solo developer, designing and implementing every layer of the application, from the procedural story engine to the real-time image generation pipeline.

The most challenging part was architecting the client-side RAG system that keeps the AI "honest." Each suspect needs to remember their alibis, the killer can't accidentally confess, and contradictions must be catchable. Getting Gemini to maintain story coherence across 6+ episodes and dozens of interrogations required careful prompt engineering and a custom memory injection system.

Working with Gemini 3's native image generation (Nano Banana Pro) was exciting, generating character portraits live based on AI-written descriptions felt like magic. I also implemented procedural UI sound effects using the Web Audio API to give the game a polished noir atmosphere.

This was my first time building a game that's truly infinite. No premade assets, no scripted stories, just a prompt and Google's AI creating a unique murder mystery every single time.

Muhammad Iqbal Hilmy Izzulhaq

Updates

Muhammad Iqbal Hilmy Izzulhaq started this project — Jan 30, 2026 12:56 PM EST

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