The game starts with the main character sitting in a car. Searching the glove compartment reveals a user manual that serves as the introduction to the game, an explanation of the (super basic) controls, and a very vague hint about your objective: find out who you are, where you are, and what are you sent here for. It is also accompanied by a mysterious invitation to a hotel in a middle of nowhere forest.
You are already at the destination, after a brief walk and some light introductory puzzles, you enter the mysterious hotel. You find locked doors everywhere, some are locked with a simple number combination padlock, some with dial locks, pin pads, and a bunch of more obscure ones. All the tropes from mystery movies are here, sliding bookshelves, hidden buttons, unusual items scattered around, weird symbols that seem to form a pattern that you just can't put your finger on. Ripped out journal pages are scattered here and there, strange clocks with too many hands, a piano room, a biliard room, really, the game nails the "mysterious hotel in the middle of nowhere" vibe perfectly. In case you are worried about jump scares, the game has no jump scares.
The art style is lovely. The game basically uses 3 colors, but it does so masterfully. The hotel, and all other areas look interesting, I have never felt that there is a certain area I disliked, or that certain areas got less attention than the others.
It may not seem like it in the beginning, but the entire play area is quite big, and most of the puzzles can be solved in any order. This is a bit in contrast with The Witness. While The Witness is even bigger, it very clearly presents you with a set of "guiding" puzzles when you encounter a new area, and they teach you the new mechanics. Sometimes you can't even access the later (harder) puzzles, before you solve the early ones. Lorelei on the other hand is completely off hand. It gives you almost the entire play area immediately, and sometimes it was not clear for me whether I can't figure out this puzzle because I'm dumb, or it's because I'm supposed to maybe see another puzzle first, that will clue me in on the solution to this one. This isn't really a negative, it's just something you should keep in mind, if you can't solve something, just go somewhere else.
The protagonist has "photographic memory", so anything you ever read, see, or watch, is recorded in the menu, and can be accessed any time. This allows you to actually concentrate on solving the puzzles, rather than backtracking back and forth between the clues and the puzzle itself.
The game makes you feel super smart when you nail the harder, longer puzzles. I would categorize the puzzle difficulty into 4 groups. 10% are obvious, 50% are solvable with some thinking, 20% are I have to come back to this later, and the last 20% are ok I can't, I have to ask for help. Even in this last 20%, most puzzles fall into the "oh I regret asking for help, I could have got this" category, but some are definitely "there is no way I could have figured this out".
The hotel has 20 "shortcut" doors, that don't contribute to the story itself, they just act as passages between various parts of the hotel, so that you can traverse quicker. There is also some light collectibles that are entirely optional, and they act as a nice break from the actual game, when you are stuck on puzzles.
The story of the game is super good, and easily climbs up to the top 5 for me. It is very obscure, and hard to put things together, but in the end it manages to form a cohesive story, with a beginning and an end, unlike something like Signalis, where I felt like the writers themselves didn't exactly know what they want, and just threw a bunch of stuff at the wall, hoping the community will come up with something (still a very good game though). It's hard to go into more details without going into spoilers.
The game has no fillers, padding, time wasters, or procedurally generated stuff, it's a complete package filled with proper content. I finished the game in 22 hours of play time, and ended on 99.2% completion. I bought it outside any sale for about ~22 EUR. It is easily worth more, especially compared to corporate games that charge an arm and a leg, and are still crap.