After more than five years, Kickstarter users who backed the Sixense STEM — an eagerly anticipated, long-delayed virtual reality motion controller — are all being offered refunds, as Sixense abandons its original plan for a mass-market device. Sixense is sending its 2,383 original backers a message today, and it’s also offering refunds to people who preordered the STEM system after the 2013 campaign closed. It will continue to produce hardware for businesses, which is a relatively common trend for VR companies.

The Sixense Kickstarter campaign raised $604,978, and CEO Amir Rubin says Sixense raised around $500,000 more through preorders. He tells The Verge that Sixense made the decision in the past few months, near the end of a tortuous path from 3D-printed prototype to full-scale production. “We were struggling to take [the STEM] into mass manufacturing,” says Rubin. He says those problems were recently solved, but the company decided against moving forward with the mass-market hardware, opting to make small numbers of an improved but significantly more expensive device.

The Sixense STEM was innovative, but it’s gotten lapped by other controllers

“Struggling” is something of an understatement. Sixense has produced a number of STEM development kits, but it’s spent years fixing design problems on a consumer equivalent. During that time, companies like Oculus and HTC started adding motion controllers to their VR systems, making the STEM redundant for many people. “There’s no need to clutter the consumer market anymore,” says Rubin, if other companies are producing relatively cheap headsets with motion controllers.

Some backers decided this was true years ago, and they’ve been disappointed and infuriated by the STEM’s perpetual state of limbo. It was originally set to ship in mid-2014, but it’s been consistently pushed back a few months at a time. (The first comment on its last public post simply begins “Refund, refund, refund.”) Rubin says he’s returned funds to individuals who asked, which is around 20 percent of the total backer base, according to him. But last year, he said that Sixense’s board of directors wouldn’t let him offer a blanket refund yet. Rubin says that changed partly because Sixense made $20 million by selling part of its stake in MVI Health, a partnership with medical device company Penumbra.

Remember those VR lightsabers?

Lots of VR controllers hit Kickstarter around 2013, filling a gap for people who bought Oculus’ newly released (and similarly crowdfunded) Rift VR development kit. Most of these companies have either floundered or given up on their consumer plans since businesses are far more likely to need an expensive, specialized device that works best with a few applications. Sixense, for instance, offers a full-body tracking system for VR job training simulations.

But Sixense — which was also behind the 2011 Razer Hydra controller — may be the best-known of these companies. It appeared at trade shows with then-novel experiences like a VR lightsaber demo, years before Lucasfilm released the first official lightsaber game. Rubin says the STEM helped inspire Valve and HTC’s Vive motion controllers at a time when most Oculus Rift apps relied on keyboards and game controllers. (Valve engineer Jeff Bellinghausen is on Sixense’s advisory board.) And “the backers put the STEM system on the map,” says Rubin.

Last year, I spoke with some backers who still found the STEM’s design promising. It tracks controllers using magnetic fields, while most major VR systems rely on cameras or other visual tracking options. (The Magic Leap mixed reality headset’s controller is based on similar principles.) Rubin says he thinks some people will be legitimately disappointed by the news that the STEM — at least, the model Sixense promised — isn’t shipping. But for many people, it will wrap up a disappointing saga that’s been running for almost the entire history of modern VR.