Congratulations on taking the plunge into game development! It's a great way to learn and hone your skills.
When it comes to developing a game with PHP, there are a few design patterns you should consider. The Model-View-Controller (MVC) pattern is a great way to structure your code and keep it organized. It separates the data (model) from the user interface (view) and the logic (controller). This makes it easier to maintain and debug your code.
Another pattern you should consider is the Observer pattern. This pattern allows you to create objects that can be observed and notified when something changes. This is useful for game development as it allows you to keep track of changes in the game state.
Finally, you should consider using a framework such as Laravel. Laravel is a great choice for game development as it provides a lot of useful features such as routing, authentication, and database access. It also has a great community and lots of resources to help you get started.
Good luck with your project!