Developer Noel Berry originally announced Skytorn in 2014, calling it a "procedurally generated adventure exploration game set in the skies of a post-apocalyptic world" in an old post to the PlayStation Blog. Skytorn was later pegged with a 2017 release date, yet the year has come and gone it's nowhere to be seen. However, it seems Skytorn is still very much a thing.
I discovered Skytorn while digging into Celeste, an upcoming mountain-climbing platformer from Matt Thorson, creator of TowerFall. Berry was part of Celeste's development team, and Thorson is part of Skytorn's, which also includes several other designers you can learn more about in this FAQ.
In a June 2017 blog post, Berry announced Skytorn was going on hiatus to allow Celeste to take center stage. Now that Celeste is gearing up for release, Berry plans to rev up Skytorn once again.
"The plan is to revisit Skytorn and finish it up now that Celeste is done," Berry tells me, adding that a PC release is still planned. "However we still have quite a bit of work to do on the game so I can't really say when or how long it will be before it sees a release."
In the meantime, you can sample Berry's flash game expertise in Celeste Classic, a free prototype of Celeste which he and Thorson made in four days. As previously reported, Celeste proper is considerably prettier and more ambitious, with over 600 stage-based levels in all.