The reason we don't have Brokeback Mountain: The Game is that the technology just isn't ready.
The game industry, perhaps more than any other medium, has some problems with innovation. Sure, every now and then there are unique games that defy classification, but for the most part big-name developers don't like to stray from tried-and-true formulas. 2K Games president Christoph Hartmann sees this, and says that the drought of new ideas will continue until we reach graphical perfection.
Hartmann claims that the problem revolves around empathy, or lack thereof. Speaking in an interview with GamesIndustry, he said that videogames are still inferior to movies in terms of conveying emotions, particularly the ones that drive characters and let the audience connect with the people on the screen.
"Recreating a Mission Impossible experience in gaming is easy; recreating emotions in Brokeback Mountain is going to be tough, or at least very sensitive in this country," Hartmann said. "It will be very hard to create very deep emotions like sadness or love, things that drive the movies. Until games are photorealistic, it'll be very hard to open up to new genres. We can really only focus on action and shooter titles; those are suitable for consoles now."
In essence, it's far easier to identify with characters when they aren't straight from the uncanny valley. "To dramatically change the industry to where we can insert a whole range of emotions, I feel it will only happen when we reach the point that games are photorealistic," Hartmann continued. "Then we will have reached an endpoint and that might be the final console."
Hartmann's argument makes sense in a way, but he seems to confuse story genres (like tragedies or romances) with game genres. We certainly have the technology to make a Citizen Kane video game, but how fun would it be? While we may not have a first-person shooter that works as a romantic comedy, developers like Quantic Dream are starting to challenge the limitations of what a narrative-focused game can achieve. "Action" games aren't incapable of being emotional anymore; BioWare was able to elicit powerful emotions (for better or worse) from the Mass Effect trilogy, which had fairly standard cover-based shooting as its core gameplay. Start dusting off your innovation hats, because that graphical plateau may already be here.