I want to show different initialization ui, according to the player's progress when my game starts. How should I implement it?

You can add a custom Initialization UI (a custom Naninovel UI will work) under the Engine configuration. You can also add a custom Initialization script in the Scripts configuration (you can choose any script in your project as long as it has been added to the Scripts Resources). A guide on how to customize a UI can be found here, I highly recommend checking out the calendar UI example project linked right below the video to get a working example of a semi-advanced UI: https://naninovel.com/guide/user-interf ... tomization