Well, on the whole, people don't really go and see theater. The participation brought by games can be done in other ways, but most people do not. Art and entertainment are changing to accomodate the lowest common denominator. The vast majority of the population, if asked to reflect on a play you made them see (as there is no chance in hell they would do so of their free will), would most likely say somthing that could be boiled down to "lol gay". Video games are enjoyed by almost everyone, including the uneducated masses. This is the reason I think that video games have underwent a shift to entertainment instead of art in the recent years. It became accepted. The generation that started on video games as new media grew up. They accepted in in ways those who came before them did not.
Thus, things like murder mystery games and interactive theater are no longer given any attention by the vast majority. Video games are, and they have began to suffer for it. It is odd. For example, I would argue that the campaign of Call of Duty 4 was art. It told a tragic and shocking story, ending with assuring the player that all the death and suffering the characters went through would go unknown and unappreciated by the public. Its plot follows the formula of the modern tragety to the letter. Normal men, in this case soilders, brought down from what little they had. But then, there's the online. That is pure entertainment, mass competition. It has no artistic value.