Darkest Fear is a puzzle exploration game containing switches, boxes, doors and various dynamic light sources (like flashlights and lanterns) that the player uses to solve puzzles. In this game Thomas Warden searches for his lost family members (his wife Susan and his daughter Helen) through fifteen missions in a monster-ridden old hospital. He has to talk to other patients and find ways to travel deeper into the hospital.

Thomas' most important enemy is darkness. Venturing in the dark deals damage, so he has to open windows to let the light in, find light switches or carry lanterns and flashlights. He is also able to lit fireplaces, carry mirrors and talk to other characters. There are multiple endings and the plot continues in the sequels Grim Oak and Nightmare.