After playing for some hours I may be somewhat stuck in Knock Knock. The game is not clear on what you must do or how you must do it. It's okay, many games do this and it's nice for us to discover on our own (Dark Souls). However I reached one of the last levels and it seems that if you do not proceed to the next level/room/dream/nightmare whatever you want to call it, you may be getting a "Game Over" screen the next time you will try to advance to the next level just like you normally would do.
Knock Knock have a very creepy and depressive atmosphere. Seems to be a great game to play in the upcoming Halloween. You will always feel that you are surrounded by someone or something, yet, you feel alone at the same time.
Now this is very clever: There are things that really help to create a tense mood in the game with such basic gameplay elements. Let's say something is approaching you. You hide but you are still visible. It's okay, because it does not matter if they can see you since it's you that can't see them, because, if you see them/it then it means they are real and if you believe they are real, then you must be hallucinating meaning you are losing it.
The game have more than one way to end, or to not end at all, in fact. Depending on some actions across the game, when you proceed further a larger enemy may be something for you and a very different one for me.
Immersion tip: In this game the sound of doors opening and closing are quite regular. If you have a sound system with a Subwoofer, placing the Sub below your desk near one of the corners gives you a much more real feeling that something or someone is really knocking a door in your house. This adds to the atmosphere giving you a more intensifying experience especially when everything is silenced and then "BAM!", someone shuts a door, and you feel the vibration.
In my opinion you don't get those jump scares we sometimes see (faked or not) on Youtube videos from games like Amnesia. In this game instead of "AAAH, Oh my God & Buddha, that is scary!!!" I got something more of: "That is creepy... go away, please, I don't want to look :( Just... leave me alone... :( " and that, is really rare in a game.