On Twitter it frequently comes up that TW is a great aid to Gaming Campaigns. Its being actively used.
@mthomas768 has posted several blog posts about how to use it for gaming support, like:
At the moment we don't have any online Game Campaign TW to point to show how good it is for game planning.
This is part of a more general problem with SHOWCASING TiddlyWiki. We do not do enough to show what TW can do with full online examples.
Josiah