One of the coolest mechanics is the way the monsters behave - they're unpredictable and can sneak up on you at any time. The game also has a bunch of jump scares that'll make you scream, and the atmosphere is super creepy and immersive. You'll feel like you're really there, trying to survive in a haunted restaurant.
The sound design is also worth mentioning - the creepy noises and breathing sounds will make your skin crawl. And just when you think you've got everything under control, something will happen and you'll be like "ahh!". The game's ability to surprise you is what makes it so addictive.
Five Nights at Freddy's 2 on Steam
