There’s an element of reality lacking from even the most atmospheric video games. As a survival horror buff, I take masochistic pleasure in waiting until the sun slinks away for the night before turning off all the lights, drawing the blinds, slipping on headphones, and creeping through old mansions and other haunted grounds.

But for as fast as my pulse races during such excursions, I can’t forget that I am ultimately safe and sound in my apartment, furnace or air conditioning chugging along, my thumbs twiddling instead of scratching desperately at a locked door to get away from some grotesque beast. Affliction: Zombie Rising (Free) aims to rip you out of your comfort zone by introducing a level of immersion not often seen in video games, much less mobile ones.

You play Affliction the same way you’d snap photographs of an overexcited subject who just can’t sit still long enough to say “cheese." Holding up your phone or iPad as if to take a picture, you twist and turn to swing your first-person view around compliments of the iphone’s gyroscope. For devices that don’t include gyroscopes such as the original iPad, physical movement is replaced with a virtual stick. I tested the virtual controls on my iPad and they performed fine, but woe to those who don’t get to experience the gyroscope controls, because they, along with the chilling atmosphere, make up the game’s main draw.

Affliction takes place in a warehouse with bloodstained floors, boxes heaped onto rusted shelves, and wall-to-wall shadows pierced only by the narrow beam of the flashlight attached to your weapon. (Take that, Doom 3! I still love you, though.) Once the game begins, low moans and tortured screams emanate from the darkness moments before zombies slowly detach from their surroundings and shuffle toward you from all sides.

You can play Affliction in broad daylight if you want, but that’s not how developer Naquatic wants you to experience its horror thriller. Do what I did. Wait until nightfall, stand in the center of a dark room with your iOS device in your hands and your headphones on, and see if the sounds of shuffling footsteps and hungry growls don’t make you break out in a cold sweat.

Affliction‘s gun controls are equally intuitive. Tap the screen to fire–striving for headshots as zombies materialize from the darkness, of course–and hold your device level and swipe your finger down and then up the screen to reload, just like pulling back on a real slide. The experience of physically turning around to cover all your sides, blasting zombies and sliding your slick finger down the barrel of your virtual weapon to shove more rounds into the chamber before the undead creeping up behind you can take its first bite, is arguably as absorbing as any VR headset.

There is an obvious downside to such a physical control scheme, however. Affliction proceeds in waves. Kill all the zombies in one wave and the next one begins, throwing progressively faster zombies at you in greater numbers. After about four or five waves, the room–the real room, I mean–started to spin from twirling around to bust caps in rotting heads, and I found nausea a more stalwart foe than the waves of undead. It’s a double-edged sword, that dizziness: it made the experience even more engrossing, but it kept me from playing for too long at one time. Fortunately, as of version 1.1, you can switch over to virtual controls from the main menu, but at the cost of the intended virtual reality-like experience.

My only complaint with Affliction is its lack of content. The game features a few weapons that you can unlock by surviving set numbers of waves or as IAP, but only one map, the warehouse zone. Besides unlocking guns–which you’ll be able to do more of as Naquatic adds new ones–the only other draw is toppling other players from the leaderboards by outlasting them against the undead hordes.

As I played, I couldn’t help imagining larger, more realized game experience that used Affliction tech as a foundation. The two-player mode, wherein Game Center pairs up players to watch each other’s backs, adds a molecule of replay value, but as it stands, Affliction amounts to an impressive faux VR tech demo that, while impressive and fairly priced, probably won’t hold your attention for long.