WordPress uses categories and tags as both a way for search engines to find your blog and as a way for you to organise your content.   There are different ways of doing this but the way I find works best is to use categories for individual games and the overall subject matter (e.g. games, mmo, lotro, vanguard) and tags for keywords (e.g. lotro outfit, weatherstock 2012, minecraft client crash) and some sub-organisation (e.g. lotro lore, weekly screenshot).  Wordpress suggests using between 6 and 10 categories/tags as the optimal amount to use.  It does take a bit of trial and error to find which work for you but you can change them and change as you go along (you can rename them globally which can save a fair bit of faffing under the Posts> categories or tags dashboard).

Custom menus are just brilliant, especially if you play more than one game and write about more than one subject.  As you can see above I’ve used a custom menu to differentiate all posts categorised under lotro and under eq2.  These posts are then further sub-categorised into lotro outfits, eq2 decorating etc.  I tend to only put posts on the custom menu if there are a fair amount of posts as otherwise the category widget works just as well (test it out – try looking at my minecraft posts using the category widget, and then the lotro posts under the category widget.  Then look at the lotro menu above and try that out).