Like all developers, I have spend quite some time in choosing the right tools to create this game. Right now, Unity is the most popular choice for developing mobile games, but I used a completely different tool to create Fred.
I‘m a veteran user of Flash. I have been using it for many products since it first came out as a beta product called Futuresplash Animator in 1996. The main reason to use actionscript to create Fred is my experience with it. Combined with Starling and Air it is still a very reliable and sturdy environment for creating 2d games and apps for Android, IOs, macosX and Windows. Here are some of the games made with Starling to see for yourself. If you are familiar with one programming language the time you have to spend in learning another is not the right investment in time if you can create what you want to create with the familiar language.