By being incomplete. For instance, if a note just has half a message like 'The door...' and nothing more. It makes the reader wonder what's about the door? Is there something dangerous behind it? Is it a way to escape or a gateway to more horror? This lack of information builds suspense.
It builds tension through the use of suspense. By not revealing too much about the ghost at once, it keeps the reader or viewer in a state of anticipation. For example, there might be just a glimpse of a shadow or a strange sound at first.
He uses detailed descriptions of the setting. The old, dark, and quiet house creates an immediate sense of unease. For example, when he describes the creaking floors and the cold drafts, it makes the reader anticipate something spooky.
Through its pacing. 'Dear Esther' has a slow and deliberate pacing that builds tension gradually. As you move through the environment, not knowing what to expect, the tension mounts.
Iswaran likely used vivid descriptions and suspenseful elements to build up his ghost story. Maybe he started with setting a creepy atmosphere and gradually introduced mysterious characters or events.
She builds suspense through her pacing. She might start a story slowly, introducing the setting and characters in a seemingly normal way, and then gradually introduce the first signs of the supernatural. This slow build - up makes the readers feel a sense of unease as they don't know what's coming next.