Enderal: Forgotten Stories is an ambitious total transformation mod for Skyrim with an all new plot and significantly modified mechanics. Their creators were previously responsible for other Elder Scrolls mods such as Nehrim for Oblivion, but now they are moving to a commercial project that they say “hopefully will be announced this year”.
German studio SureAI announced this in the latest patch notes for Enderal. The patch fixes some issues like a flair that doesn’t cause the right amount of damage, and when the springs drop it sometimes disappears and gives a few typos.
Modders point out that continuing from Enderal means they won’t have time to patch it further or move it to the Skyrim Special Edition. You will still need the “Oldrim” version of Bethesda’s RPG to play Enderal.