I think your time is very short. The post needs to be promoted, discovered and then some time for the authors to create the content. Usually the contests run for seven days, as the post reaches the payout time.

In my opinion is better for a contest to have only one option: Have a good open ending, getting you hooked for more. This could be the main criteria to valuate the contributions.

I feel a bit contradictory No gore stories or any sort of gruesome content with You can choose freely... I would suggest No offensive or discriminatory language as a limitation and let everyone's imagination work.

Hope this helps, but you have the last word!!