The plan is to use Ian Schreiber's online course material from last year. The course is called Game Design Concepts, and should take us twenty to thirty weeks. Our study group is something like five people - a suitable size to keep meetings sane. Each of us will do reading and exercises on our own time, and then we will meet weekly to discuss the week's topics and exercises. Once the exercises start to be about actually designing something, we will include play testing into our meeting agendas. The course is about non-digital games, as these are much easier to do solo.
So, I will probably write more about the course, especially about the things I have learned, in the future.