Great horror stories are many things, but tedious isn't on the list, and that's exactly the feeling that's born of Knock-Knock's inability to explain itself. A game that doesn't tell us how to play and has no consistent rules is a frustrating experience, no matter how eerily beautiful it is. Knock-Knock's confusing mechanics give little reason to answer the door.
Knock Knock isn't quite a nightmare, but with a little more focus, it could have been a dream to play.
Knock-Knock is a game with great sound work, a nice, unsettling art style, but several flaws. Its mechanics are never explained. You can expect to replay the entire thing over again to see its "best" and "good" endings. With no real way to see if you've made decent progress other than to play until the end. Since there is no traditional save system, this can turn into quite the gamble, and if you make it through the game a second or third time only to find out that you didn't "earn" the best ending, you may kind of feel like you wasted your time.
Knock Knock is one of the most original psychological horror games ever made, yet it has remained very much an unappreciated title.
Ultimately, the title's strange machinations make it both compelling and hands-in-the-air frustrating. When you are frightened needlessly in life, time moves forward inevitably and brings daybreak even as you hide under your bed sheets. In Knock-Knock, you're not just battling your own fear; you're trudging uphill, woefully unequipped, against an opaque system of rules that never exposes itself. Look everywhere, listen to everything, study, document: It doesn't matter. You could still be left wide awake, perpetually replaying the same night over and over again—a true nightmare if there ever was one.
Knock Knock can be an alright experience if you want a type of horror that feels slower.
If you are looking for a different gaming experience, and are willing to invest the time into finding out the story, then Knock-Knock could well be the strangest game you'll ever play.