At the beginning you just have to explore the complex, searching for clues about what has happened. As you penetrate ever further and advance, you'll start to hear the confessions of the last people who were there.
That said, it will be a while before you'll start getting properly scared, after discovering a horrible secret. That's when you'll realize you're not alone in the dark ... there's someone else down there with you.
When you come face to face with this creature, the only thing you can do is run – run for your life. If the creature catches you, that'll be the end of your life and the game.
Stairs is a first-person horror game where you'll be surrounded by darkness most of the time. Without a flashlight, your character won't be able to see a thing ... although sometimes it's best not to see anything anyway.