Here is a link to prioritize our members for the closed alpha
https://www.playkeystone.com?referrerId=592484d74cde6f955909983a

Its some combo project by DE and some other dev team. Free to play as well. I dont know much about it though. Figured id put my name in there for us just in case

Also, here is the original post by DE about it
https://forums.warframe.com/topic/799797-keystone-closed-alpha-announcement/#comment-8702604