Good game! I should note that the graphics are executed at a very high level.

Love the prop-hunt XD ..... and this radar getting crazyyy!!! Great work and nice implementation of the idea. Great Work!!!

(I am now in a rush to test as many games as possible to help, so please do not mind the cursory reviewing style.)

Semi-on-the-fly remarks:

1. Both English and Portuguese, cool, seeing that there is written in-game information according to the instructions! :D (I am no Lusophone, but have an interest in foreign languages, so, maybe one day. :) Even though not one of my current target languages, but I dabble in Spanish.)
2. Why are the credits hidden in the Settings submenu?
3. controls ARE layout-independent, great!! (I have an AZERTY keyboard.) And arrow keys are enabled.
4. time continues while reading; fair enough
5. at least two misspellings in the first text I see ("astk" -> "ask", "Stoneheng" -> "Stonehenge"), so you might want to double-check
6. music from both the menu and in game are great! Also, sound effects and visual atmosphere. Very soothing and somewhat ‘nostalgic’/mysterious music.
7. Left Shift works for running, but Right Shift does not; could be useful when playing with the arrows and mouse
8. We do not know what the time limit is from the beginning, which is stressful! Is it on purpose, or do you have to read it somewhere?
9. small movement of the head while staying still, nice detail
10. Cheaty thing: you can pause while reading.
11. I really like the concept of not being too explicit about how things are working, and letting the player know through indirect texts; this actually reminds me of "Alone in the Dark" (which is the true first "Resident Evil"!).
12. Lost while reading a book on the third element (Eye of Dagda) (and only had one shapeshifter, before deciding to read everything). XD Did not watch closely what time it was, but I feel you cannot really first read all the books and then win the game on your first time, the timespan limit is too short — except if you are a skilled fast reader.
13. Playing again: GREAT, the objet I had identified as a shapeshifter the first time (the lamp near the beginning) is not! So, there is randomness, or at least, variation! :D :)
14. Is jumping really useful?
15. Finally figured out that ROLLING THE MOUSE WHEEL is how you change objects!! I think you should be more explicit about this command; you can still add it to the game page.
16. The second object apparently tells you how many Shapeshifters are in the vicinity.
17. And according to a book, the third is about protecting yourself from spells? But no-one attacks you?
18. Spoiler: The only way I really managed to find a Shapeshifter, as in my first run, is by seeing an object move (and listening). The second object helps, and I still do not really get what the third is for. Silly me, I realize the name is written: "Radar"! XD So, I guess you have to use the sound rhythm. Seeing how the recharge is infinite, it looks like it is even more powerful than the second object! (Ah, not the sound, but rotation. Oh, BOTH sound and rotation. X) Way more precise than the second object!)
19. Found all five!

Takeaway: the atmosphere and books are great for immersion and getting into the lore, but you really have to dedicate a first run to read properly, and actually, the names for the 2nd and 3rd objects are quite a giveaway as to their usefulness, so I even think reading is in fact totally optional; still, I enjoyed doing it. :) I also think the concept is original, and fairly connected to the theme (ghosts, although not horror, this time!).

I think the game becomes too easy using the third object! I would advise either removing or nerfing it; if you remove it, then the 2nd object could be made either infinitely usable or stay the same, depending on the difficulty you are aiming for. Jumping did not seem useful, and running only little. I really like that the Shapeshifters are not located the same depending on the run; I wonder if they can switch places DURING a run — if not, I would advise they do! I also wonder if I missed some mechanic, seeing how one book told about protection. Adding some danger (other than the time limit) could be interesting. Also, I think you should state the time limit (although I may have missed it from a book? I only noticed one saying that it becomes dangerous after an undefinite number of hours).

This is a very original and interesting atmospheric hide-and-seek game, with fine details, and my only complaint would be that I wished for some more mechanics and usefulness of the books! Hey, it is a good sign when the public wants more. :)

Thanks for the game!

PS: as JUSTCAMH says, I was expecting various ghosts with different abilities from the books, which could be a very good way to give more variety to your game! :)

PPS: I realize the ghosts are very Pac-Man-like. XD