Cross-Platform Family Event App

I’m putting together a simple mobile app for a personal family event and I want it to run on both Android and iOS from a single code-base. The app’s main purpose is entertainment: I need a built-in game that guests can play during the gathering—think light, fun and quick to learn... (Budget: ₹600 - ₹1500 INR, Jobs: Android, Flutter, Game Development, iOS, iPhone, Mobile App Development, React Native, Unity 3D)