Why would anyone still make games without a multi-player component these days when there are so many advantages to having it and the internet is widely available? I'm glad you asked; here are five good reasons to make single player games:
Difficulty
If you haven't been living under a rock you have seen people complaining about the difficulty of MMOs. For years many players claimed raiding in World of Warcraft was too hard, now others (like me) call it too easy. In single player games one can just have an adjustable difficulty setting, cheat codes, or a quicksave function. In online games - not so much. Multi-player gaming is all about fairness and often about competition. People don't generally like playing with others who operate under different rules. Cheat codes, for example, are usually disabled in online games to prevent individual players to gain an unfair advantage. Other settings have to fall by the wayside as well. If you have a look at good old Starcraft you can see that it was possible to adjust the game's speed on the fly during the game. When you had to make tough decisions or micromanage your troops you could slow down the game and speed it up again in more dull periods. In multi-player you obviously couldn't do that. Or imagine a Bioware RPG with a multi-player mode. How annoying would a "pause" key be for multi-player?
Modability
Dragon Age: Origins, like many CRPGs before it, comes with a powerful editor that allows users to make modifications to the game. Some mods are innocent such as the GNR extender for Fallout 3 which increases the library of songs played by the in-game radio station Galaxy News Radio, or less innocent but still harmless like a nude skin for desire demons in Dragon Age: Origins. Some mods add new content, characters, items, or features to a game and some are simply a way of cheating.The cool thing about single player games is that all these modifications are perfectly fine. Once you go multi-player, not so much.
I once had a mini LAN party at my place where we only managed to hook up two computers. Two of my friends played Diablo with each other (I can't remember whether it was Diablo I or II), starting from scratch. At one point one of them cheated by adding some items to his character. Needless to say, the game exploded in a cheat-war and we stopped the whole thing soon after that. Giving players in multi-player games the ability to change their own characters or the world at will? Not a good idea.
A good editor and a good community can greatly improve a game after its release and allow players to tailor their game to their needs. This can only really work in single player games. (Unless you count cosmetic changes such as the mods in World of Warcraft.) Those are a lame joke, however, when compared to the mods for some single player games.)
Immersion
I've been talking about immersion a lot lately because Dragon Age:Origins just does such a fantastic job at immersing me. World of Warcraft doesn't feel immersive at all, but I think that primarily due to a design flaw. (No real story, lame quests, no characters, etc.) However, even a really well designed multi-player game will have immersion issues due to the presence of other players.
Imagine the 12 year old kid hanging out in Orzammar, talking about your mom, or people yelling "WTS 10 stimpax PST" in Megaton. Even if you go to dedicated role-play servers in an MMO, immersion is hard to achieve. Stories are not coordinated well and the majority of players just aren't professional writers. You also can't really have cutscenes or voice-overs when dealing with human players.
Overall, if you want to tell a story and make suspension of disbelief possible, make a single-player game.
Heroism
When I play games, I like feeling special. In single player games the player is often the hero, sometimes there's also a choice to play the bad guy instead. Either way, the player character is important, the story centers on her. Nobody wants to be some flunky in the infantry unless that fate entitles them to be the only survivor of a rout and to go on a roaring rampage of revengeTM afterwards. In a multi-player game that is impossible, especially if it's a massively multi-player one.
One especially bad example of this is the Ring of Blood quest line in World of Warcraft's Nagrand region. In this quest a group of players goes through a series of gladiatorial combats until they have defeated every available opponent - the winner then being announced in zone-wide chat as the new champion. When the expansion was new and everyone was leveling in Nagrand, you would see a new champion announced every couple of minutes. So much for heroism.
Balance Balance is really the ugly stepchild of multi-player games. If one way of playing a game turns out to be significantly stronger than another, players start playing only that because they would feel inferior otherwise. If you have a real-time strategy game in which one faction is superior to another, battles would start feeling rigged and the game wouldn't be very popular. In WoW, much of the development effort is spend on making sure that no class is too strong or too weak compared to both the enemies and other players. If you read the official forums you might even think that class balance is the only thing anyone cares about.
In single player games, balance doesn't matter so much. Mages in Dragon Age: Origins for example are far superior to any other class and rogues play like a weaker version of the warrior. Most people don't care about this, simply because they don't have to put up with betters in game. You can play through the game using a party with no mages at all and still have fun. It doesn't matter so much that there would be a stronger option available to you if you don't have other players to compare to. In multi-player, your suboptimal choices will be shoved in your face and you might get scorned for them. You might even be kicked out of your guild in an MMO if you don't play to the standard that guild requires. In single player, none of this matters.
Conclusion
I didn't name the advantages of multi-player here as this is not really a comparison. All I want to do is point out that being multi-player enabled isn't always a good thing and that I'm happy that there are still pure solo games around.
That said, I'm sure there are more than these five reasons to like single player games. What are yours?
