Welcome back to Computer Game Design! I'm really excited about getting back to teaching this class!
The game engine we will use for Fall 2017 is still being determined. In the past, I taught this course using MonoGame (the open source version of the XNA engine used for Xbox Live games). That is still a consideration as that engine is still being used for modern releases (FEZ, Bastion, Axiom Verge, etc.). If that engine is not used, we may use either Unity or Unreal. Most likely we will not use the Java engine used in the recent semesters.
If you want something to do over the summer, pick up Reality Is Broken: Why Games Make Us Better and How They Can Change the World by Jane McGonigal - Amazon. It's a great book and a relatively quick read. We'll be using it throughout the class.
Let me know if you have any questions!