By day, Dredge is as quaint as it first appears. Push off at sunrise in your dilapidated boat, seek out spots teeming with fish, and sell your haul to locals back at port.

But at night, this sneakily scary adventure bares its teeth.

Treacherous rocks appear out of nowhere in the fog. Distant beams of mysterious crimson light beckon. And massive, shadowy things swim beneath your boat—or rise out of the waves and try to swallow it whole.

Simultaneously welcoming and foreboding, Dredge lulls you into a sense of serenity at first. The core loop—catch fish, sell them, and use the profits to upgrade your trawler’s engines and cargo space—is familiar fun. And Dredge’s uncharted waters shine on iPad’s larger screen, where the extra real estate makes it easier to scout fishing spots with your spyglass (and those with newer devices can crank the frame rate up to an impressive 120 fps).

But like a fish fooled by a bright, wiggly worm, it’s impossible to avoid taking Dredge’s bait—until the sun starts going down and you suddenly realize you’re an awfully long way from the nearest harbor. This ebb and flow between relaxing routine and mounting tension makes Dredge so unforgettable.

The game’s unsettling story doles out dread in drips: Who is the Collector, and why does he send you off in search of sunken relics? What’s the source of the eldritch horrors plaguing the islands? In this brilliant, slow-burn thriller, the greatest discoveries—and most frightening revelations—lurk just below the surface.

Be wary of other boats you cross paths with after dark. That innocent-looking trawler is likely the lure of a Night Angler, an enormous fish that can tear your hull to pieces. When you see a passing vessel, cut the engine, kill the lights, and pray the beast doesn’t notice you!

A live-action film adaptation of Dredge is in the works from Story Kitchen, a production company that specializes in bringing video games to the big screen.

Dredge is the debut from New Zealand’s Black Salt Games. The company comprises just four people—and they’ve all spent more time fishing in video games than in real life.