Last week at both the Mobile World Congress and Game Developers Conference we got hands-on with the HTC Vive’s Tracker peripheral once more, and one of the best uses for it we saw was to enable full-body tracking in VR.

With three Trackers attached to our feet and waist, we walked around Cloudgate Studios’ Island 359 with a pretty accurate representation of where our bodies were in VR. We were able to kick dinosaurs in the face, opening up a new means of control and sense of presence. This particular system was created by Cloudgate itself, but will other developers be able to benefit from this type of tracking?

HTC says a separate version of full-body tracking they are working on will be shared with developers.

Speaking to UploadVR at MWC, Alvin Graylin, President of Vive in China, said that HTC had been working on a “similar system” for full body tracking in its China research lab, and would be open sourcing it for all developers to implement into their experiences for free.

The key to this system, as Graylin explained, is that it’s entirely optional. Island 359, for example, is still entirely playable with just two Vive controllers. You don’t need the Trackers to be able to experience the game but, if you do, you’ll have a more immersive experience. If the system is easy to implement and other developers catch on then this could be the biggest selling point for the Tracker, which is unexpected given its original pitch was to attach it to other objects, not yourself.

This system could also be hugely important to games like shooters. Currently, games like SUPERHOT VR (not on Vive) give you an invisible avatar, save for your hands, which can make it tricky to avoid bullets. Giving you a visible torso could help make those experiences a little easier to understand. Then there are the potential applications for more accessible VR film making and more.

Vive’s Tracker will be available to order for developers later this month for $99.99, and will be going on sale to the public for the same price later this year. Along with full body tracking, you can expect to use it to shoot guns, fight fires, and even play with friends.