I have included a "Difficulty" option, if you set it to "Ease" you will have 50 lives, but, the achievements will not count. You will have the achievements if you set it to "Normal" or "Hard".
Also, I want to say that Ninja Stealth is a stealth game, you will have to stop, analyse and then move. You can't just run like crazy from one door to another, this is not a "Endless Runner" game.
For the detection system, I think people are reading the reviews from the early versions and think there is problems with it. But, there is nothing wrong with it, this part of the game was entirely recreated .
Maybe players are being detected for other reasons and don't notice, If you move a box in front of any detector, you will be detected. Even if you are using the camouflage, the detectors will detect a box if it is moving inside the room. The camouflage protects you, if you stay still. There is no random detections of your character.
But, if you find anything wrong with it, please report it on the game's forum.
And remember, if you don't want to keep seeing the tutorias, you can deactivate them on the options menu.