They are Watching your Every Move...
This mod adds many horror entities that will haunt you at day and night.
It also adds new features, structures and items.
I recommend a blind playthrough, but if you want to check out most of the stuff added, then there is a creative mode tab containing every block, item and spawn egg.
Credits to bloxzen/bloxyy for major help with the mod - the screenshots, plenty of the ideas and most of the structure work was done by him.
It may be a bit buggy as the code is not perfect and MCreator has its limitations.
Enjoy
