Thoughts

I played Amnesia and I still don't know if the monster had some special hability. I guess the only thing was that if you looked at him your sanity decreased. It could have an effect that if you look at him you begin breathing heavily and making more noise but idk...

Don't you mean this guy? There's no single "Monster" in any Amnesia game.

Some spoilers for the three Amnesia games (it won't let me hide them):

This is a Grunt, the enemy type you'll see the most. There's also the Brutes, or even the Suitors from the Justine add-on. None of them really possess any powers beyond their physical force.

There's also the man-pigs from the second game, and the ghouls and the wraiths from the third.

As for main antagonists, there's Alexander from the first game, the titular Machine from the second game (which gets way too much flak imo) and Empress Tihana from the third. The latter two... I really don't think they work that well considering their associated themes. Especially the Machine would be weird, for obvious reasons.

There's also "The Shadow" from the first and third, which is not unlike the Entity, though more protective. Since it lacks any real physical form, I also can't really see it as a killer.

Okay well, glad you enjoy it. 😊