You have to collect three white cubes in order to beat the game (which are gameobjects/mesh from unity simply plopped down for you to collect), because of this, the game feels more like a test build rather than a full release of a chapter. My advice is that if you're not going to have any backstory as to why you are where you are and why the grim reaper from billy and mandy is targeting you then at least make the player/character wake up on the hard ground or something similar to achieve that feeling of "okay I woke up here so now let's figure out why."
There is a health bar in the game and if you stare at the enemy for too long you will slowly lose health and you will be teleported to a different part of the house, the enemy doesn't exactly chase or attack you and if you touch him he doesn't cause any damage. This is not good, you have to realize that humans are the most afraid of "the unknown" so when you have a creepy guy immediately show up without any tension or context, it's ultimately not going to scare you. Try showing your creature/enemy less and build tension to when you see it, an example would be that you're walking down a dark hall and something in front of you runs by really fast from right to left or vice versa, you don't know what it was and it begins to make you imagine as to what it could look like which isn't good for the player. The health in the game is okay but make sure it has a reason, maybe the player can be silently walking down a hallway but the creature was being them the whole time and suddenly the player's health starts to slowly drain indicating that it's right behind them/nearby.
Now this is my final critique for now, it's a bit nitpicky but hear me out. The music, it's not fear inducing, well it could be but it's played right at the beginning of the game, throughout being around the monster, and etc. Let's say that when you see the monster, the music suddenly stops or it slowly fades and a more eerie, atmospheric track comes in, or maybe even silence will do. If you choose to use silence then adding a heartbeat or breathing from the monster or something would have to replace the silence, sounds and music is vital to horror. There are a ton of ways to implement music and sounds into your game so really I'll leave that up to you to decide.
Again this game has a lot of potential and I look forward to seeing more of your work! I really liked the monster, it was unique from what I've seen from other games. Keep up the good work!