Well, I considered it a good thing that visitors stay for a long time and read many pages of the library
The site grew 'organically' from a set of a dozen articles. New articles were added and cross-linked from the existing, as they seemed to fit. Sometimes pages that grew too large were split, but not entirely cleaned up, therefore the redundancy. (Just trying to explain the current state, not necessarily defending it).
A better catalog, search options and maybe directory-like pages might help.
A tree-like structure I feel unable to employ. Well, I tried, but it failed already. The information by nature is much more mesh-like than a tree, since it's seldom clearly hierarchical. The picture that fits best is a mesh - each node explaining an aspect of game development, and from each node there are dangling some more articled with additional views, details and ideas.
I once had a more graphical representation in mind (needs Java browser plugin):
http://www.simugraph.com/library/relview/index.htmlThat shows the above mentioned mesh, and if you click the nodes you can choose articles (if a node has some). But that was too difficult to maintain. Yet maybe some day I might try to make an overview like this for the wiki pages, too.
Having said that, if you have ideas how to improve the current content and structure, please let me know. I might not be able to do big, particularly structural changes, but improving cross-linking or page contents I can.