If I get to use a classic mechanic like the doors or mask I try to give some variety to that mechanic or some change.

Making an original mechanic is a challenge in fangames because you have an idea that seems original to you but then you discover that there was another game that had the same idea long before

Unfortunately a game will never be original and if you manage to make something unique or original is that you were lucky.

But as for original animatronics actually if you can create an original character as for example, an animal never used in fnaf fangames.

I think I was lucky enough to be the first to create a hyena animatronic

or maybe there is a game that I do not know that used the idea of a hyena as animatronics long before me and if so then too bad...