The creator of trainyard, one of the best-selling games on the iPhone share the beginnings of his venture:
"One day, while sitting on the train as during my daily commute, the concept for a game involving trains filled with paint came into my head. I did a bunch of paper planning, and eventually coded up a quick Flash prototype nicknamed “PaintTrain”. It was awesome. I set to work making puzzles every day during my commute for the next few months, still thinking I was making a Flash game...."