The Marketplace
Oh No!
Gamers don't know what we want. We say we want features, but we never use them. We want different games, but we don't buy them. We complain that all the games are 'the same', but those are the only kinds of games we buy. Take a look at this example: when Deus Ex and/or System Shock 2 were in development, were you upset that they wouldn't have multiplayer on release? Did you buy the game and be upset about the lack of multiplayer? Did you complain in email or on the forums? When the patches finally came out and you could play multiplayer - did you? How much time did you spend playing with your friends in Deus Ex or SS2?
Do you really think that your complaints (or at least those of other gamers) were that justified, considering how few people play multiplayer Deus Ex and SS2? Was it really worth the developer's time and money to patch multiplayer into the games? From a business perspective, I can almost guarantee that it was a bad decision. From a gamer's perspective, I would prefer different features, or even for the developers to have saved some money and used it for something else.
Yet, multiplayer is something we all like to have. At least so long as we can say we have it. Maybe so that we can try it a couple of times. Games without multiplayer sell poorly sometimes. Other times, they sell but people complain incessantly across the internet to the developer. These are the same people who will try it 'a couple of times' before going back to the single-player mode, or playing another multiplayer game.
What's this got to do with turn-based games?
Civilization II is a classic game which sold well, yet it spawned few clones. X-Com, Jagged Alliance, Gary Grigsby's Pacific War and Fallout are other examples. Great games that sold well, or at least 'good enough', yet never created a massive demand for games similar to them. Why not?
They don't have the latest and greatest. Multiplayer is difficult to implement effectively. 3D graphics and sound lose much of their effectiveness if the field of play is static. However, there is an even more important point that makes real-time games more attractive.
Turn-based games have it within them that you can't get satisfaction if you don't put in real effort. That satisfaction doesn't pay off immediately either. Researching armor upgrades in StarCraft results in almost-immediate effects. But researching technology in Alpha Centauri takes many turns (each of which can be very long), then you have to design a weapon or item around that technology, and finally build it. This satisfaction is very important in gaming, as it's a behavioral reinforcement tool. It gives you the pleasure that keeps you playing more.
TBGs give that satisfaction, but it's not instant and overwhelming. It's not easy to get - you have to work for it. The difference between TBGs and RTGs is like the difference between a manual and automatic transmission. Unfortunately, many gamers have been spoiled by RTGs and instant satisfaction, and it is difficult to turn the clock back.