halo 3 obsessions

Saw this documentary about teens and gaming.  It was on the Fifth Estate a couple of weeks ago.  Its fitting as my son is quite obsessed with Halo 3 and has gone to tournaments. Most of his peers now are older than him...either grade 10, 11 or 12 and beyond.  Its an interesting social world: people he met online and now sees face to face.  I can not get my head around it as I am not at all interested in playing first person shooter games, or any games for that matter.  Although, I do go online to use Facebook.  And, I do play some games:  Lexulous, World traveller...both of which are on Facebook.  I try to relate to my son and other teens who play games online.  But I also feel helpless to make him stop playing.