Ive worked on apps for big brands and various software development agencies away from freelancer, so understand the necessary steps to get the app right first time.
It sounds like you want a container for an existing game you have finished?
So this type of project is split into the following sections:
1. Discovery: what the goals are, a definitive feature list, user journey, deciding on the software development stack and developing some style guides and constraints,
2. Design: we will design a storyboard with wireframes and some UI in adobe xd.
3. Develop and test: we will develop your application using Google Flutter framework an
4. Deployment and maintenance plan.
Im sure you and I both have questions for each other. What is this app worth to your business? Initiate a chat.