Hey! Been there exactly. It’s an opportunity for you to catch if you can. I suggest firstly to explain him things as they are that it will take a long time, will require to learn a lot of new things and a lot of work. If he takes on this then you will be partners in this venture and will study together how to build his game. Next regarding 3d I suggest you together with him to check the few development environments that exist for games in order for you and him to understand how much learning and effort will it take in each env. Then you can evaluate and choose from what exists today. In our case we decided to settle on a simpler 2d game first in order to achieve some results quickly. Targeting 3d in the second game. So we choose to use Construct for the first game and we actually delivered it to the Play Store (it was important to finish). We didn’t finish the second and third games but they were already started in Godot and then Unreal Engine, respectively. This is our experience. Your mileage may vary.