I guess it boils down to the overuse of plot twists and the fact that some people are so used to them they actively start searching for clues to plot twist the very instant they start a game, or movie.
Doing that ruins your experience/enjoyment of the ride, though..

too many games use it, so it's always in the back of my mind now. Also, I found Lissy to be too harsh about Betty and that kind of made it apparent that something was off about her.

When you sit down on the docks to draw in your sketchbook, Lissie will sit down on the pier in front of you. I thought Edward would have drawn her in the sketch, but when I opened the journal to examine the sketch, she isn't there.

I noticed while playing that Lissie never interacted with her suroundings in any meaningfull way. She would walk around, balance on walls, practice gymnastics every now and then, but she never picked up or moved anything. When Edward and Lissie agreed that Edward was tired and weak, it struck me that Lissie never helped row the boat or carry his "Heavy" suitcase. She would tell him to hurry up but never help out in any meaningfull way. She didn't fysically try to stop Edward when he dug up the grave, she never ate or drank, nor did she provide anything beyond conversation. I also found hur outrage over Edward's obsession with betty a bit strange.

A smaller thing i noticed as well was that she never pointed out anything the main character didn't allready know. Like in the church, when she was standing on one of the benches but never pointed out the paper next to her before emmideatelly after it became vissible to the player. She never found a single piece of paper, in fact.

Lissie doesn't actually do anything. At all.

She also always appeared wherever you were.

And really, the moment you find the first article of clothing that was "Betty's" made it very clear Edward is mentally unstable and making things up.

I just played the first 20mins. I figure she's a ghost or a figment of his imagination, literally came to this decision in the boat, lol. I'm refunding as she's super grating so interesting to see I was at least somewhat right judging by what you're all saying.

I don't remember the exact moment, but Lissie sometimes says strange things. When she said that children can do monstrous things I already had my suspicions and her words kind of confirmed to it to me.

I then considered that he may have killed his sister when she was young and Lissie was an imaginary version of her. Or even that he was actually Betty and had developed multiple personalities after her brother died.

Edit: the "Home Alone" achievement is kind of a huge signal to anyone who has not figured it out by then.

The relationship between the two was really off right from the get go. The way Lizzie talked to Edward and the way he replied was very odd and didn't fit the 'she's his young ward' scenario. Then when they arrived in the town and Lizzie seemed to be able to travel everywhere instantly made it clear that she wasn't real.

I didn't figure it out :D haha though I was surprised that she always arrived everywhere very quickly and she was not carrying any luggage and inside Teddy Bear's, there are only his clothes but I realize now, after knowing it.

She doesn't have *any* sort of luggage. Clearly they are not engaged, so they would have separate luggage, yet the main character only brings a single suitcase for a many-days ordeal. The developers went to lengths to make it look realistic with that packing, but either they made a huge error... or Lizzy doesn't exist.

The "appears wherever it's convenient" I'd play down and say it's understandable developer laziness.

It's very obvious because she never interacts with the world.

The first thing that gave it away for me was the letter Edward sent to the Norwegian family, which we can read near the beginning (it's on the table on the sitting room). He's very scrupulous about arranging his stay with them, yet he never mentions he'll be accompanied by a 17-year-old girl. You expect the presence of a second guest to be a major detail to communicate.
Also, the idea that this nerdy man who, we learn, never leaves his house would have a ward of that age felt immediately off. How would that happen? Did he adopt her? Is she a near-adult orphan? Why aren't we given any back story about it, despite being by far the most notable thing about his character?

More early clues to Lissie's real nature. When she's in the tree, if Edward worries she might fall and get hurt, she replies, snarkily, "Well, that's not really likely, is it?"

When Edward blurts out, "There are no ghosts!", Lissie answers with a sarcastic "I don't know about that".

This might be more evident in hindsight, but when Lissie starts waxing poetic about nature on Day 2, Edward asks, "Where do these strange thoughts come from?", and she retorts, "Well, you're a funny egg, old bean!" (implying those were indeed HIS thoughts).

No luggage. No mention of her in the letter to Anna. Aaand - where does she sleep? Main bedroom is locked until the last day. She suggests that our hero should go to sleep in guest bedroom - it's clearly unused on second day. Ruth's bed is made as well. The couch is taken. She doesn't sleep anywhere.

To be clear, I still enjoyed the twist, especially due to his dramatic execution that was linked to Edward's true state of mind, rather than being just some "Gotcha!" moment, a la "Ah-ah! Didn't see THAT coming, did you?" (which, no, we kinda did).

Strongly suspecting something is also different from something being immediately evident, there's the thrill of not knowing when and how it's going to come into play.
Plus, the exact nature of Edward's various figments isn't clearly stated at any point. They're not ghosts, and they're "alive", in some sort of way. The devs hinted at the matter of their existence not being as clear-cut as one might think.

It would have been addressed in the sequel, had the sequel been made. Sadface.