Gamasutra's Advanced Input/Output week continues with a look at "holodeck" game development. If placing your body in a fully-immersive virtual world is the game developer's ultimate goal, then the holodeck is the holy grail. Of course, not all game developers are chasing the dream of a Star Trek-inspired full-body virtual world simulation, but the teams behind Project Holodeck and Turbo Tuscany certainly are. Project Holodeck is the work of a team of USC students in the Advanced Games Program who are working on various aspects of a virtual world, from art to game design to optical and gesture tracking. James Iliff is producer on the project, which he helped start back in March 2012 alongside Project Holodeck director Nathan Burba and one Palmer Luckey, founder of the hot virtual reality company Oculus VR. "Our goal was to create a platform that offered about 90 percent of the immersion of these super expensive systems, but for less than 1 percent of the cost," says Iliff. "And with that consumer-level price point, we wanted to start creating virtual reality games that everyone could enjoy and engage with." There are ways in which one experience near-holodeck-level immersion, but as Iliff acknowledges, developing a consumer-level system is the challenge. He and his colleagues have worked with professional-level motion capture systems that implemented multiple cameras, mocap suits and trackers all over one's body. That's on top of head-mounted displays with wide fields of view. All of this together provides near-100 percent immersion, says Iliff. All of this sounds expensive, and it is -- prohibitively so. Iliff estimates, "[It'd be] $200,000 for a mocap stage, thousands more for these military-grade HMDs, and you could scarcely imagine that a consumer could fit this into their homes. And because these systems were primarily used by research communities, the content was primarily research-related. There was nothing inherently entertaining about it whatsoever." A more reasonably-priced holodeck experience is within reach. Project Holodeck utilizes the Oculus Rift head-mounted VR goggles for video and a combination of PlayStation Moves and the Razer Hydra for limited body tracking. A ventilated backpack holds a customized laptop that powers the experience in a space that's around 12.5 x 10 feet. The team is using Unity for its game engine. All together, hitting 1 percent of the cost of an industrial-grade "holodeck" system is feasible. Zombies on the Holodeck! from the Project Holodeck team Meanwhile, at Finland's Aalto University, Tuukka Takala has been pushing forward with immersive worlds since 2010. With the release of Oculus Rift, he created a Unity-based demo called Turbo Tuscany, which takes people to a VR rendition of the Italian region. His Holodeck-inspired dream is called RUIS (Reality-based User Interface System). Mainstream accessibility to full-body VR immersion is also at the forefront of his project. "We set out to create RUIS software platform, with the intent to make it easier to build virtual reality applications using affordable, state-of-the-art interaction devices," he says. With different combinations of Kinect, Razer Hydra, PlayStation Move and Oculus Rift, and a few rubberbands, he shows how hobbyists can jump into a holodeck-like experience.

Lessons in full-body immersion

Being on the edge of a new generation of holodeck systems means Iliff, Takala and their colleagues are already running into the challenges of full-body virtual immersion, and coming away with important lessons. "The biggest lesson we've learned is to take full advantage of three spatial dimensions, or otherwise the game will feel more like a port of traditional first-person game instead of a made-for-VR game," says Iliff. This mentality should be applied to all aspects of the game: "design, art, interactive items, AI, audio and everything in between." Developers should consider the intimacy that VR facilitates between the player and the world. "For instance, place the most interesting and detailed models near eye-level, so players will get up close and examine the hell out of them," he says. "The closer an object is to a player's face, the greater the sensation of depth and parallax. Make weapons as juicy as possible, and assuming you are using motion controls, have players manually reload their guns with new clips." Have slow-moving projectiles which players can step aside and dodge, he adds. Place written notes on tables that players can pick up to bring closer to their eyes for reading. Allow players to jump, climb, press buttons, pull cords. "By focusing on the things that involve – and invade – a players' space, you will be taking the fullest advantage of virtual reality," he says. Audio is also extremely important in such immersive situations, Iliff says. In the Project Holodeck game, Zombies on the Holodeck, for example, the sound of rain changes depending on if the player is exposed on the street, under an overpass or under a metal overhang. "If your not taking full advantage of virtual space, then you're missing out on an opportunity to subconsciously affect the player in a tremendous way," he says. "Subtlety is all the rage with virtual reality gaming - because for the first time we can actually do it." Takala says developers must "Get over the wow-factor of virtual reality, and provide your players with substantial gameplay." VR and holodeck-style experiences are novel in and of themselves, but not enough to keep even the most enthusiastic VR fans engaged, he says. RUIS' Turbo Tuscany "What might work in a 10-minute demo doesn't necessarily work in a full VR game or application," he says. "Ask yourself why you want to involve physical movement in your application, and how that enhances the user experience. This is an important question since motion controlled interfaces are often laborious to implement." There are also ergonomic aspects that developers need to take into consideration (avoid the "gorilla arm", for example), and what kind of repeated movements players need to act out that might hurt the experience. Jumping with an Oculus Rift strapped to your head isn't ideal, and even though your body is virtual in VR, it's very real in the physical space. "We had to be very careful about not breaking stuff in our office or crushing Oculus Rift signal box with our feet when testing the Turbo Tuscany demo," he says. "We kept tripping on cables from the Oculus Rift, and the solution to this would be to convert the Rift to a wireless version by creating a custom battery pack and using a wireless HDMI and USB transceiver."

When will the real holodeck arrive?

Game developers who talk about immersion often talk about how a true holodeck experience is way off in the horizon. And they're probably right – let's face it, when one of the biggest challenges is where to put your coffee table when you're using full-body VR, we've got a way to go. But people behind these systems are taking on the challenges, nonetheless. Iliff says a perfectly-simulated reality will come either as a system that manipulates real light and matter, The Next Generation-style, or the system will directly manipulate the brain's perceptive powers, The Matrix-style. There may also be hybrid systems that emerge, he speculates, depending on the tech that develops: perhaps haptic gloves, VR and augmented reality contract lenses would work in tandem with a machine that taps into your brain. "These are all very idealistic visions that we aspire to, and I think we're getting pretty damn close with the current tech we have on hand," he says. "But there is still a long way to go. Considering how far we've come since the Industrial Revolution, I would say that a perfect simulated reality of some form – like the holodeck – will emerge in at least two centuries." Takala acknowledges that head-mounted displays are about as close to holodecks as game developers will get in the near-term. Perhaps in 10 or 20 years, he says, the issue of decent haptic feedback is solvable. "If the matter manipulation technology behind Star Trek’s holodeck proves to be beyond our reach, it might be that the next best thing will be achieved via plugging our brains into a computer using optogenetics or other neuromodulation techniques," he says. "That could take more than 20 years though." But once humankind gets to that "holy grail," then what? "I personally would use a true Holodeck for acting out scenes from movies like One Million Years B.C., Ghostbusters" and Inception," he muses. "I would also hang out with a virtual George Carlin, and do some extreme sports like mixed martial arts and base jumping. "The question is whether the geeks of the future want to return to the 'meatspace' once they have accessed a perfect Holodeck." Read more about VR and Advanced I/O on Gamasutra's special event page this week. If you'd like to read the full email Q&As with Iliff and Takala, check out Kris Graft's Gamasutra blog.