First off, Hard Mode Shadow Sonic's official design is above! This is a design created directly by TheCyVap, for those who didn't already know (since this is on the official FNaS wiki already)

I'll just go over some of the basic stuff that was already confirmed for it before:

The nights will be reduced to 6 minutes from the absurd... whatever length they were before, 10 minutes? I dunno... Anyways, the game will scale with this to compensate.

Secondly, the Goldens will be distributed throughout the game in the same way they were in the original version's Hard Mode, something I also confirmed a while back.

But here's the big new change...

Hard Mode's getting overhauled (mechanically, not graphically).

And we're taking the "Hard" in "Hard Mode" very seriously.

Unlike the original FNaS 5, Hard Mode will be treated as an extra campaign for experienced players to give them an extremely tough challenge, adding new mechanics to every character and making the game extremely difficult even from the start. I predict that Night 9 or 10 will actually rival the difficulty of the base game's max mode, that's how tough I want it to be.

That's all for this wall-of-text update! I wanted to share this because it was really exciting to hear that I was actually allowed to do this lol.