Mac hackers

Inspiration

Shadow Companion was inspired by our love for Halloween aesthetics, dark-themed UI design, and interactive virtual companion apps. We wanted to create something spooky yet friendly — an app that feels alive, reacts to users, and builds an emotional connection through design, sound, and interaction.

What it does

Shadow Companion is a Halloween-themed virtual shadow pet app. Users can interact with a living shadow character, play mini-games, earn XP, unlock new skins and backgrounds, read daily shadow diary messages, and experience special festival modes during Halloween. All progress is securely saved with cloud sync.

How we built it

We built the frontend using React Native with dark-themed UI and Lottie animations for the shadow character. The backend was developed using Node.js and Express with PostgreSQL as the database. JWT authentication handles secure login and cloud data syncing. REST APIs manage user profiles, game scores, XP, diary entries, and assets. The entire system was containerized with Docker for easy deployment.

Challenges we ran into

The biggest challenges were synchronizing animation performance with low battery usage, managing smooth real-time interactions with the shadow, handling offline-to-online data sync, and designing a spooky UI that remains user-friendly and safe. Integrating sound effects without causing lag was also a key technical challenge.

Accomplishments that we're proud of

We successfully built a full-stack mobile app with real-time interaction, cloud-based user progress, smooth animations, and engaging mini-games. The dynamic shadow reactions, daily diary feature, and festival mode are some of our most creative achievements.

What we learned

Through this project, we learned full-stack mobile app development, REST API design, secure authentication using JWT, cloud database management, animation optimization, and team collaboration under time constraints.

What's next for Mac hackers

Next, we plan to add AR mode for real-world shadow interaction, introduce more mini-games, expand the diary system with AI-generated messages, improve social sharing features, and launch Shadow Companion on the Play Store.

Built With

• asyncstorage
• docker-compose-**tools-&-libraries:**-axios
• express.js-**database:**-postgresql-**authentication:**-jwt-(json-web-tokens)-**cloud-&-hosting:**-render-/-railway-(backend)
• firebase-(optional-for-assets-&-notifications)-**apis:**-restful-apis-**devops:**-docker
• lottie-animations-**backend:**-node.js
• openapi-(swagger)-**design:**-figma