Heres a random idea, but it might take alot of soccing.
Have 5 'Idieas' hidden in special enemies that take more than one hit to kill. You'll play as Elliot (Can't spell his name) or Claris (Can't spell her name) and collect blue sphears (Rings) and hunt down the 5 Idieas. Once you find them all you automaticly turn into NiGHTS and can move as freely as you want (Fly as high as you want, stay uderwater as long as you want etc.). Like a super form, NiGHTS will turn back into the boy/girl and you'll have to get 50 sphears to turn back.
And for the colour, use a shade of pink for lighter areas.