For the last 13 years Linden Lab has been developing Second Life, one of the most popular virtual worlds online. It's easy to scoff at the game, with its dated graphics and simplistic activities. But it's still remarkably popular, averaging 900,000 monthly active users. Part of its appeal is the economy, which allows anyone to buy and sell virtual goods. Talented users can sense what will soon be popular, be it clothes, furniture or vehicles, and make them with 3D modelling software. They're then imported and sold on the in-game marketplace for "Linden Dollars," which can be exchanged for real-world cash. Designers made $60 million this way last year.

Now, Linden Lab is applying the same approach to virtual reality. The latest headsets are packed with potential, but crafting compelling software is expensive. To make a decent VR sandbox, you need a game engine, a team of talented engineers and artists, and people to manage hosting and distribution. That's fine for a large video game developer, but unrealistic for a museum, a charity or a book publisher. With Sansar, Linden Lab hopes to create "a WordPress for social VR." While the company handles the technical aspects, crafty creators are free to build unique assets. Anyone who wants to make their own world can buy these items or import their own, quickly building a shareable and reliable VR experience.

Mars is but one example of what people could make. If NASA or SpaceX wanted to show people the red planet, they might create a world in Sansar. The scene whipped up by Linden Lab is a beautiful, but surprisingly empty playpen. I can't pick up boulders, for instance, or hack away at discarded machinery. Altberg admits that interactivity is "fairly limited" in Sansar right now, but promises to expand it over time. The "scene" we're standing in now was constructed in half a day, he stresses, and is meant to illustrate the platform's flexibility.

A hazy outpost on Mars.

A world on the platform could be small or stretch many kilometers. Teleporters will help you to stitch them together, creating globetrotting tours or history-spanning adventures. Like Second Life, the format is skewed toward social interactions. You could hold a business meeting in VR or show aspiring homeowners around their dream property. You could gather at the lake with some wakeboarding fans or talk about politics in a park. The limitations of a "scene" will be set by its creator, but Altberg expects them to naturally start small. "If you think about how you function socially in everyday life, most of the scenarios you run through are with small groups of people," he said. "Family, three or four people. Coworkers, you might have a meeting with six people."

Altberg hinted, however, that there could one day be public events such as parades and football matches that demand larger groups. "Ultimately, we'll get into the hundreds of avatars that you can have in this place concurrently," he said.

Sansar will facilitate basic games and group play, too.

I feel a tap on my shoulder and take off the Oculus Rift. Peter Gray, senior director of global communications for Linden Lab, is preparing to load another scene for us. In the final version of the game, world switching will be triggered with an "Atlas" search directory. Today, as part of an early demonstration, one of the team's engineers is forced to intervene. I can let it slide, though. After all, I'm standing in London, while Altberg is logged in from the company's offices in San Francisco. A few technical kinks are to be expected. Social VR on its own isn't new, however; I've had similar meetings in AltspaceVR and Hello VR's Metaworld.

As Gray prepares to load an ancient tomb, I ask him about the creation side of the platform. What will developers use to create new assets in Sansar? Pretty much anything, apparently. Right now, Sansar is in what the company calls "Creator Preview." It's effectively a closed alpha, allowing a small group of people to upload items and populate the marketplace. They can use "a variety of third-party tools," Gray says, such as Maya, a 3D modelling tool popular in the video game industry. "We want the experts in 3D content creation to continue using the tools they're already familiar with," he stresses. On a desktop PC, Bjorn Laurin, Linden Lab's VP of product, shows me some software that will allow people to lay out their scenes. It's a simple drag-and-drop interface with a searchable inventory and top-down perspective. I watch as he pulls trees into position and decides where the sun and other important light sources should be.

The "Creator Preview" will ensure lots of assets are ready for the public launch.

"In the future, we'll introduce additional tools aimed at people like you and me," Gray explains. "You'll be able to adjust terrain using voxels, that sort of thing." Before I can quiz him further, I hear my headset connecting to the next scene. I slip the Rift back on, stepping into ... nothingness. Just a blue, empty abyss. Confused, I spin around. Behind me, about 20 meters away, is a large hole. Altberg is standing on the other side and gestures for me to follow. "Come in the door over here," he urges. I point with the Oculus Touch controller and hold down the trigger, an arcing path appearing in front of me. I release the button and watch as my avatar bursts forward. To go beyond the Rift's room-scale tracking, teleportation is a must. I repeat the process a few times, blinking my way across the chasm until I'm standing next to Altberg again.

Immediately, I feel like Indiana Jones. An Egyptian tomb is laid out before me, symbols and torches lining the walls. It feels different than the Mars scene. A little more real. The scene was created using photogrammetry, a technique that combines 360-degree photography and positional data, usually collected through LIDAR (the laser-based equivalent of RADAR.) A research organization and a Paris university collaborated on the project, crunching the data for roughly a day using a supercomputer. A tiny slice made up of 50 million polygons was given to Linden Lab, which crunched it down to 40,000. The project was finally imported into Sansar, creating a scene that anyone can now walk through, examine and touch.