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Yuuichi Eguchi
Yuuichi Eguchi

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I Built a Virtual Pet Game Where You Raise an AI

What I Made

Ainimo is a virtual pet raising game. You start with a baby AI that can only say "Goo..." and watch it grow smarter as you care for it.

🔗 Live Demo: https://ainimo.vercel.app/


Features

1. No External AI APIs

No ChatGPT, no Claude, no API calls. All "intelligence" is simulated using rule-based logic and internal state changes. This creates an authentic "raising" experience.

2. 4-Stage Growth System

Stage Intelligence Behavior
Baby 0-24 Simple syllables: "Ba!", "Goo..."
Child 25-49 Basic words: "Want play!"
Teen 50-74 Keyword-aware sentences
Adult 75-100 Context-aware responses with memory

3. 4 Actions

  • Talk: Build friendliness and gain XP
  • Study: Increase intelligence
  • Play: Boost friendliness
  • Rest: Restore energy

Tech Stack

  • Next.js 16.0.7 (App Router)
  • React 19.0.0
  • TypeScript 5
  • Tailwind CSS 3.4
  • localStorage/IndexedDB for persistence

All game logic is implemented as pure functions for testability and maintainability.


Why I Built This

I wanted to create an experience of "raising an AI" rather than just "using an AI." The challenge was making simple rule-based logic feel like genuine growth—no LLMs required.


How to Play

  1. Visit the app
  2. Choose actions to raise your AI
  3. Progress auto-saves in your browser

Supports both English and Japanese with automatic language detection.


Give it a try and let me know what you think!

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