You could make an app that has in app purchases but it doesnt require them to get really good at the game. I hate it when I have to build a structure etc and it says it would either take 12 hours to build or like 20 gems to finish it instantly and im sure everyone else does too. And also try to release it on all the major platforms (ios, android, windows and eventually branch out to computers)

Be observant .Observe your environment. Identify a problem that can be solved with programming. Solve the problem and sell the solution for money. Another way is to register with a freelance programming website like freelancers and do freelance job for money.

Please not that your environment consist of companies, industries, schools, businesses etc around you.