Plane with quaternion (no Euler)

Do a 3D game with a spaceship where you handle the rotations using quaternions.
A spaceship always moves towards its forward vector. However, it can change directions by tilting left or right to turn !

No Euler angles allowed (angles in degrees from 0 to 360)

NinjaMission Build

Use what I learned in Basic Unity 3D and about Dot products to create a simple stealth and backstab mechanic.
I should have:
A character with movements and rotation
A minimum of 3 enemies
A text or icon showing on the screen that tells you if any enemy currently can see you
A text showing on the screen that tells you if you have a backstab opportunity :
No enemy sees you
You are behind an enemy
You are looking in the direction of the enemy