Believe it or not there was a time when gaming wasn't as social of an event as it was today. Lots of games were single-player experiences and that's the way we liked it. We jumped into a world, spent hours there, and didn't feel socially irresponsible after doing so. If you were itching for social gaming, you went to an arcade, and it would satisfy every multiplayer itch you could possibly have. But those days are long gone, arcades are all but vanquished from the West, and solo gamers are looked down upon. Kotaku's Michael McWhertor has an interesting article about it.
There is some cause for concern for the solo-only player. Massively successful games like Infinity Ward's Call of Duty 4: Modern Warfare and Valve's Left 4 Dead offered shorter campaign modes in favor of a more robust multiplayer feature set. And StarCraft fans may be more than perturbed about the late release of StarCraft II: Wings of Liberty, already sliced into three campaigns, largely due to delays with Battle.net, Blizzard's multiplayer service.
If more publishers and developers follow suit in shifting more focus to multiplayer, will the lone wolf suffer?
The addition of multiplayer to games that have relied on their single player strengths is done for a number of reasons, the most obvious of which is that the game buying public has simply come to expect it as a series sequelizes and evolves. It's an oft-demanded feature from the community, even in series that tend to be strictly single-player.
Personally I don't expect games to be multiplayer, and sometimes I really don't want it! But the gaming atmosphere has changed drastically over the last twenty years, could multiplayer games now be considered the norm?