To me it sounded like they stole his concept and design. He added them on Test Flight which will share an app for testing so it may be possible to reverse engin

To me it sounded like they stole his concept and design. He added them on Test Flight which will share an app for testing so it may be possible to reverse engineer it (I don't know) but I imagine they built their own game based on what he shared with them. Be careful what IP you share with others.