Partial Information is a way of hinting at what is to come, but not giving the story away. Horror is a progression. It goes from a sense of unease, where the characters suspect something bad is happening, to dread where the characters know something bad is happening. Partial information can be used to create the initial unease and to progress that to dread.
How can the characters plan if they don’t know what they are facing?
The answer is that they cannot make definite plans, which is a good reason not to give them detailed information. Keep them guessing, and in the dark, or half-light at best. This can make some players distinctly uncomfortable. I know players that are perfectionists, and not knowing what is coming is a nightmare for them, regardless of the monster under the bed!
These tips are taken from my Scarier Horror Play book. You can get 40% off this book at DriveThruRPG using this discount link. You can get 40% off all new releases as a loyalty discount if you join my contact list.