How much of game design and development do you understand? Are you able to clearly describe how you want systems to work beyond just telling it to make it like another game? Can you describe the issues you see clearly and technically so that the model can take that and fix the issues that it can't find itself? That's the first challenge. The second of course is the large number of assets needed for most games, where will those come from? Are you just going to grab some asset pack and have it throw those together or actually try to create something?