LOS ANGELES -- At the Electronic Entertainment Expo, all seemed right for virtual reality. Players were waiting in snaking lines -- some for up to seven hours -- for a chance to step into fantasy worlds. Crowds watched as players wearing VR headsets over their eyes reached out to pick up objects or shoot enemies that only they could see.
More than 125 VR exhibitors were at E3 this year, up 130 percent from last year. Yet adoption of VR among consumers hasn't really taken off in the three years since it captured buzz in the wider world. An estimated 6.3 million headsets have sold worldwide -- indicating that, even among the world's 2.6 billion gamers, few have picked one up.
Experts point to several reasons behind the slow adoption -- the technology can cause motion sickness and it is costly. It's also been hard getting people to try it, developers said. And showing virtual reality experiences on flat screens doesn't give people a good enough taste of how different the experience really is.
"How do you advertise a color TV on black-and-white televisions? It requires people walking down to main street and seeing it for themselves," said Steve Bowler, president and co-founder at VR game developer CloudGate Studio.
What virtual reality needs, experts say, is a killer app. And firms are pushing to find it, building up their own platforms and funding developers to bring games to their own headsets exclusively. But this kind of fragmentation has resulted in a confusing market and fewer games for players, thus giving them fewer reasons to spend their dollars on this young trend.
Mike Fischer, chairman and co-founder of VR game developer CloudGate Studio, told a panel last year that platform fragmentation "keeps me up at night" after so many new companies jumped into the VR market -- although he says that things have improved a little since then.
Devoting extra resources to creating games for different devices can be particularly difficult for smaller studios, whose creativity drive much of the virtual reality market. In fact some developers, such as Jeff Pobst from Hidden Path Entertainment, say they rely on funding from platforms such as Oculus to get their games made at all.
These exclusive deals between developers and VR companies make it hard for consumers to know which expensive headset will get the game that they want to play -- leading them to put off their decision, analysts said.
A monopoly, while simple for consumers, wouldn't be perfect either, experts said. Competition is important, and different headsets' characteristics inspire different types of games. HTC's technology is designed for larger, room-sized experiences that often require gamers to stand. Sony's experiences are largely seated. Oculus provides a mix of the two.
Even big players in the virtual reality market acknowledge that locking any game to a single device could be problematic.
"We actually think that content in the VR space makes a lot of space for developers and publishers to look at the market from a platform agnostic standpoint," said Joel Breton, vice president of Global VR Content for HTC. While HTC helps developers create games for its own platform, Breton said it doesn't hold them to any sort of exclusivity deal.
More companies are also beginning to work on cross-platform solutions.
Developer tools such as Unity and Unreal are streamlining the process for developers who want to port their games between headsets. Ubisoft, one of the world's largest game publishers, has committed to releasing virtual reality games that work the major three high-end headsets, allowing people who own different headsets to play with each other. Sony spokeswoman Jennifer Hallett said the PlayStation VR has several titles that also work on other platforms, including Ubisoft's "Star Trek: Bridge Crew" and "Eve: Valkyrie" -- which started as an Oculus-exclusive title.
The VR companies are also trying to do more to work together. Jason Rubin, vice president of content at Oculus, said in an email interview that he doesn't think that there is harmful fragmentation in the market for consumers or developers. But his firm tries to work with competitors to push the whole industry forward, he added.
But other major publishers seem to be waiting to see how the market plays out before revealing their plans for virtual reality.
"We believe VR will be a major opportunity, but widespread adoption will take time," said Electronic Arts in an emailed statement.
For consumers eager to try virtual reality, however, that may mean waiting at least another development cycle to let the market fill out.