The mass off people would be necessary because a group of people wouldn't be overwelmed by 3 zombies but they would be by 20 zombies
Who says it has to be a group? Can't it be one guy or girl?
I'd be overwhelmed by three zombies if I ran out of bullets.
What about two friends who decide to venture out of their protected area (basement, attic, etc.) to get food. A zombie comes of nowhere, and bites one of them. The friend has to make the decision to either 1) Kill his friend OR... 2) Risk his life.
OR
A guy who is trying to cover up a bite from his group.
OR
The POV of a person who is going through the human to zombie/infected creature.
OR
A guy who keeps a family member/friend, who has been infected, chained up in the basement. He cannot decide to kill the family member/friend and be free or stay and wait for a cure. He decides to wait. One day after going out to find food, he comes back to find the family member unchained.
https://www.youtube.com/watch?v=U6MlaIe1ljs
Chomp.
OR
A group of survivors stuck in a basement or other tight space. It's simple, dark, gritty, and claustrophobic.
OR
A guy walks downstairs to find his mom/friend/family member being eaten. The zombie/infected person is running after him, and chases him to a small room. The guy is stuck in this room, with a vicious zombie/infected person waiting outside the door eager to get in. He must use simple, small, everyday objects to outsmart and kill the zombie.
OR
Friend 1 shows up at Friend 2's house because friend 2 has not answered any of his calls or left his home. Friend 1 finds Friend 2 sick in his bed, and... well... I think you should know what happens.
OR
A man wakes up to find everybody dead in his home. He hears creaking noises upstairs. He goes up and goes into the bathroom. He whips the shower curtain open, to find no one there. The camera pans back to the man to reveal a zombie behind him.
OR
HUGE zombie apocalypse. The humans finally defeat the zombies, and families go back to their homes. A mother and daughter (or two friends; it depends how you have) go home, and find a diary of their friend (or father). They continue to read the diary, and in the end, they find out he/she was bitten, and is still in the house.
https://www.youtube.com/watch?v=U6MlaIe1ljs
To me, most of the scariest/most tense moments in zombie films were with without crowds and crowds of zombies. Remember that scene in the
Dawn of the Dead remake with the little girl? What about the church scene in
28 Days Later? Tar man from
Return of the Living Dead? The little girl in the basement from
Night of the Living Dead? The entire
Evil Dead (that didn't have many characters)?
Audio, lighting, and editing can give the feeling of a large crowd, a smaller space, a larger space, etc. Say you had a scene in the basement of a house during a zombie apocalypse. If you had the sounds of moaning, footsteps, and banging coming from the door and the upstairs floor, you'd think zombies were everywhere. Without sound in that scene, there is no tension. If you have a guy getting chased down a street by 3 zombies in a wide angle shot, there's not as much tension. But when you use fast editing, close up shots, intense music, and sound effects, you have a scary zombie scene.
Bye bye...
https://www.youtube.com/watch?v=U6MlaIe1ljs
Never gets old!