JujuRin Games

What it does

Main Concept JUJURin! is a lightweight web/mobile-based game about honesty, logic, and accuracy, using situations that are familiar to Indonesian society:

buying and selling calculating change dividing money rotating savings groups (arisan) simple logic quizzes

Zero-Knowledge (ZK) is used to ensure that: players’ answers are correct and honest, without revealing the answers to other players or the server.

How I built it

🔗 Technology (Lightweight & Realistic)

Blockchain: Stellar Frontend: Web / Mobile Web Focus: fast, low-cost, beginner-friendly

Challenges I ran into

🎮 Game Modes

🧮 Mode 1: Shop Change (Kembalian Warung) Situation: You buy items at a small shop and pay with a certain amount of money.

Example: Total purchase: Rp 7,500 Money paid: Rp 10,000

🎯 Player’s task: calculate the change

🧠 Role of ZK The player submits a ZK proof: “I calculated the change correctly”

Without sending:

formula calculation steps raw answer

The server/blockchain only knows: ✔ correct or ❌ incorrect

👥 Mode 2: Fair Arisan Situation: 5 people join an arisan (rotating savings group) Each person gets their turn No skipping or double turns allowed

🧠 Role of ZK ZK proves that:

the turn is valid there is no manipulation the draw results are fair

Without revealing:

the full sequence of the arisan

❓ Mode 3: Honest Logic Guessing

Example question: “If Ani is older than Budi, and Budi is older than Cici, who is the youngest?”

The player proves: “I answered based on correct logic”

Without revealing the thinking steps.

🔄 Gameplay Flow (Simple Illustration)

'''$$👤 Player$$ ↓ 🧠 Answer the question (offline/local) ↓ 🔐 Create ZK Proof: “I answered correctly” ↓ ⛓️ System verifies ↓ ✅ Score increases / ❌ Wrong'''

Accomplishments that I'm proud of

It is simple, Uses local language & context, Close to daily activities (small shops, markets, arisan), Can be played by children, teenagers, and adults, Educational without feeling like “school”