You could maybe ask people what their favorite character from Tokyo Babel is, or what they are looking forward to in the game, or something along those lines, then choose the winner based off the answer you liked the most. Or, simply with RNG, like was mentioned above.
I find contests to be more exciting when there is a chance of winning past just RNG though. So some format more similar to my first suggestion would be more fun in my opinion.
Also, there shouldn't be any hard requirements to enter, but you also need to make sure people can't cheat in any way. Might just have made it harder for you, sorry if that's the case
Oh, please no overly difficult puzzles. *Glares at Eclipsed*