Here are my random ideas with title suggestions:
Ego and Counter-Ego - Create two looks, one should reflect your usual everyday self and typical dressing style, the other should be the exact opposite of yourself.
Hidden from View - I have long pondered whether to suggest this one but in the end what do I have to lose? Two looks again, one shows your carefully selected underwear, make-up and accessories while getting ready for whatever occasion (work, school, public event, a night out, meeting a friend, date, concert, etc.), the other shows the complete outfit you are wearing above it. The latter may fully or only partially match with the underwear, or not at all.
DoneLady Cauchemar - Everyone has their fears or nightmares and one way of getting rid of them is to visualise them. So dress as an object of your worst fears or something you are anxious about.
DoneDress the Calendar - Pick a day of the week and dress as that day. The look should reflect your mood regarding that particular day.
Dress as a Number/Letter - At elementary school, first grade, we had coloured sticks to represent numbers from 1 to 9 to practice addition and subtraction. I still match those colours with any number I think of. So pick your favourite number, match it with a colour and dress it up in various shades of the same colour. The same contest can also be done with letters, as it was done by Arthur Rimbaud in his sonnet "Voyelles" ("Vowels").
As I would like to participate on any of these contests if they are started, you need not credit me with the suggestion. But it is up to you.

I may also use some of these ideas as non-contest games.