If I want to create a game for IOS/ Android, then which resolution I should set in the game.project file?

How to set correctly the resolution of the game ?

What you want is to pick an aspect ratio along with a large enough resolution, and then scale to fit while maintaining your aspect ratio. Then maybe float the UI to corners of the screen, and plan to be able to draw a little extra at least to the left / right / top / bottom of your screen.

This project shows a very good example of this

2 Likes