Well, then I guess that would be a reason why you might list Halo Series as your favorite all-time. Me, I'm more of a solitary player. Although I have a few cards for a free month of Xbox Live sitting around, I don't have the time to invest in a subscription, so I just play the regular campaign mode. When I think of my favorite all time games, it's usually because they were fairly innovative in some way that made them inherently replayable, whether you played alone or with friends. For example, I remember SNK Baseball Stars was great because it not only had great gameplay, but it was also one of the first games I can remember that let you create your own players. It's old hat now, but at the time it was a big advancement on previous games.