Each post within each blog was also very self contained. Each would cover a single element stemming from the blog's overarching theme. For example, a blog about how games improve the world we live had a post about a certain charity organization related to gaming, and a post about how the writer treated recovery from a minor brain injury as a multiplier, while blogs about game development had posts giving advise about particular elements of developing games. Every post would have a title which would summarize what the topic of the post would give a clear indication to the reader as to whether the post might actually interest them, as opposed to some blogs I have seen elsewhere with "clickbait" titles meant to draw readers in by not telling them what the article is actually about ("See What Happens When You Mix Coke and Milk. Play The Video to Find Out!!!").
Based off the blogs I have seen, it would seem that the most appropriate way to organize this blog would to be with an overarching theme of "Principles of Game Design" and have each individual post go into detail about a particular principle. Each post would be completely self-contained, but relevant to the entire blog.