The light shuts off, and you are left in the dark - for a moment. Then you notice a glow coming from the tiled floor. You peer down to have a better look. In a 3x2 space, the six tiles say:
I'm essential to life
But maybe not quite.
This is number thirteen
But add two more and you'll have me.
I'm not bright
But I still have some light.
I don't have a lamb
But I am inside one.
If you follow my lure
You may need a cure.
I am red and white, but not blue.
Instead, I'm black and violet - scarlet too.
Each of letters is glowing slightly white, with a glass covering above the letters. Next to them, there is that familiar keyboard for the answer. You reach over it and type...