Honestly the monster could use work, and the red text should be replaced with something more immersive, perhaps finding what the construction worker is there to get in the first place. "Hello :)" is kinda stupid and immersion breaking.
The entire leadup to the monster is tense and atmospheric and very spooky, but the monster itself just makes you go "oh, was that it?". If you really want the monster just popping up out of nowhere, perhaps have a buildup of some sort to it appearing or an animation. As it is, I could have had the same effect from a T posing Shrek appearing; which was nil.
Otherwise, loved the game, needs some minor tweaks and maybe even an actual goal; and saying there is a monster right at the start gets your expectation set on finding a monster which reduces the fear significantly.