6. Halo
Allow me to preface this entry by saying that I love Halo; I am a huge fan of Halo Reach online specifically, but any pleasure is gained in spite of an online community that is, in a word, infuriating. As is true of just about any online game that gives people a voice - that is, a microphone - the high incidence of children squeaking through the comms proves headache-inducing, their immature ramblings only occasionally challenged by that rarest of things; an adult with a mic. This is also one game that has a horrifying exterior community; if you ever venture onto the Halo forums - but I wouldn't advise it - Master Chief is idolised to a creepy extent, such that making any complaints about his character's arc throughout the games will ignite a fleet of flamers ready to assassinate your character like their lives depend on it. I've had an account myself banned from the forums simply for making a relatively innocuous comment about him; they are nutty, alright. But the games are awesome, so it's worth the effort of spamming the mute button whenever you log onto a server.