The Adrenaline Vault has an interesting article on the ascendancy of Mass Market Gaming. Here's a sample. As is readily apparent from the illustrations already provided, mass market computer gaming tends to cluster within certain predictable genres. The most common ones are retro arcade action, puzzle, adventure, racing, board game ports, and construction simulations. Sports titles are in a gray area, where some fit the bill, but others are becoming (or have always been) just too complex to understand, too difficult to win, or too awkward to play for many mass consumers. The only first-person shooter I have ever seen that would clearly qualify as a mass market title is Hasbro Interactive's Nerf Arena Blast, and frankly I cannot think of any major real-time strategy or role-playing games that would remotely fit the bill. Thus most of the areas where hardcore gamers have the greatest passion and enjoyment would not seem to be amenable to the mass market audience. Electronic Arts' recent release Black & White is a textbook example of how a game appealing to the hardcore crowd can look on the surface like it might also have mass market potential but in reality not have a chance: although it has construction simulation elements, the option of playing on the side of good (white), and a cute digital-toy-equivalent to raise and train, its high system requirements, slow learning curve, and long play session expectations take it well outside of what the casual consumer would generally stomach. You can find the whole article at this link.