You know there is a general reason challenges are set up the way they are. You say this is a challenge, so OK, what are the rules to the challenge? What is the reward? What is the time frame of the challenge? How will the challenge be judged? Since you are running it, perhaps tell a little about yourself, your experience in relevant fields, your connections etc. Also you need to market your challenge a little. What makes doing your challenge more worthwhile than doing a guild challenge? Or doing an Artstation challenge? Or any other challenge out there (there are actually quite a few)?

And the last point, which is all I really wanted to get to was this: There is a reason challenges are generally given a direction, but left open ended, and that is they are generally geared towards encouraging creativity and exciting the artists who join in. Yours is way too specific to generate much interest from people who want to compete. And also it is of immense scale and time consumption, most challenges try to limit both of those things.