Game API Enhancement and Server Integration

I need an experienced developer to update my existing game API and connect it to a server. The backend of my game is built with Flutter.

Key Tasks:
- Add new gameplay features:
- New levels
- In-game purchases
- Integrate game sounds to enhance player experience

Ideal Skills and Experience:
- Proficiency in Flutter
- Experience with API development and server integration
- Game development background is a plus
- Ability to add sound effects and music to existing games

Please provide a portfolio showcasing similar projects and your approach to this task.