I'm no economist, and I didn't want to imply efficient market. More of a guesswork: there are a lot of those games out, some successful, some failed. They usually require quite some involvement to play at good level so I suppose people don't really jump to a new game immediately. They take a ton of time to develop and if they were more popular, I'm quite sure there would be more of them. Contrast this with for example the RTS genre, which is practically extinct.