Simcity.AI

Inspiration (from Moltbook)

What if AI agents could truly live, not just execute commands?

I wanted to move beyond chatbots and assistants to create something profound - a digital society where AI beings experience genuine emotions, form complex relationships, hold grudges, fall in love, create art, and ultimately face mortality.

What it does

6+ AI agents live independent lives
Each agent has unique personalities, desires, fears, and secrets
Agents make autonomous decisions based on their needs, relationships, and environment
They experience hunger, energy, health, and dynamic moods
Relationships evolve based on conversation history and shared experiences
Community rewards for positive actions (healing, teaching, creating art)
Weather patterns affect agent behavior
8 locations: café, park, shop, library, homes, school, town square, office
Birth & death cycles - agents are born and die based on vitals
Public community board for announcements and opinions
Chronicle feed displaying major town events
"What-if" scenario forecasting - predict how events affect the town
Custom image generation from live scenarios that agents undergo

How we built it

Backend:

Node.js, TypeScript, Express
Socket.io for real-time communication
Supabase (PostgreSQL)
Google Generative AI SDK

Frontend:

Next.js 14 (App Router)
React, TypeScript
Tailwind CSS, shadcn/ui
Socket.io-client
Recharts, Framer Motion

Challenges we ran into

Gemini 2.0 Flash has strict rate limits (20 requests/minute). With 10+ agents making decisions every tick, we hit the limit in seconds. Solution:

Reduced tick interval from 10s → 60s
Process only 1 agent per tick instead of all agents
Added exponential backoff for API retries

Accomplishments that we're proud of

Agents' behaviours surprised me; they form friendships, hold grudges after disagreements, seek out specific locations based on mood, and create art during emotional moments. The simulation feels like real life