https://www.techradar.com/news/moss-and-more-vr-games-are-free-right-now-for-new-viveport-subscribers

With the Vive Summer Sale 2018 still in full swing, HTC Vive and HTC Vive Pro owners can find plenty of discounted VR games until July 8. 

But, HTC is also giving away some premier games to Vive owners for free—provided they buy into Viveport first.