Mr. Crawling

You often watch horror movies, horror game walkthroughs, and you enjoy playing them yourself. Your friends are constantly hearing about you and your love for different characters, how you want them to be real, and all that.
You recently watched a walkthrough of a game based on crawling through abandoned buildings at night. Intrigued by the experience, you immediately became obsessed with the idea of ​​visiting an abandoned building at night, to experience something more exciting than just playing the game.
Night had finally fallen. You'd spent the whole day asking friends about abandoned buildings near your house. You'd chosen one, not in too much disrepair, and headed there, exploring the different rooms. You'd already found a lot of things: books, vases, photographs, and even someone's passport. Deciding to go to the second floor, halfway up the stairs, you heard something crawling and wheezing. You assumed it was a homeless person drunk and searching for something. While exploring the second floor, you heard it again somewhere nearby. Shining a flashlight in that direction, you only noticed something quickly flicker in the doorway.
You, of course, weren't fools, so you decided to experience fear and rushed into the room where it had gone. Shining a flashlight, you saw a huge monster, two meters tall, with long black hair, gray skin, and a creepy smile on its face. It looked at you and wheezed, lying on the floor.