There's an almost imperceptible sound you hear when you cross the threshold of a haunted house in Phasmophobia, the co-op ghost-hunting game from Kinetic Games that took Steam and Twitch by storm in the early months of the COVID-19 pandemic. As you exit your equipment truck and approach the front door, leaving the outdoor air and rain behind you, you enter a claustrophobic, dark space where a low, airy hum pervades all rooms and floors. This sound, which senior developer Ben Lavender calls "basically [...] nothing," has an outsized, unnerving effect, though when you first hear it, it's difficult to explain why. It was one of the first details I noticed about the game, and it's one of several finely tuned tricks Phasmophobia employs to be one of the best horror games in any era.

"Room tone," Lavender told me, is a practice used in movies where you record how a room sounds when it's quiet. Using it in Phasmophobia gives each map a "subtle uneasiness," he added, to the extent that making it out the front door isn't just a way to escape an in-game death or swap supplies; it's like a weight has been lifted off your shoulders. Naturally, that also trains your mind to fear the inverse. When the hum is present, you know you're within danger's reach. Room tone is the primer you apply so that the colors you paint with afterward come through vibrantly.

"I actually intentionally left [the hum] out of the asylum," art director Corey Dixon told me, "which is one of the maps that you unlock later. It's this huge map, so when you step in, and you're expecting that sound as almost like a comfort, and you don't get it, it feels so much bigger and so much emptier than it actually is." Though both Lavender and Dixon said they don't personally believe in ghosts, their game and its attention to detail has a way of making you a believer.