May I suggest making this provably fair by using proof of work submissions as your random number source and then publishing the algorithm used by the bot so everyone can know who should win?
I for one would like to second the above suggestion.
However I am not sure if we will use the steem blockchain (or any other blockchain) to generate the random number. Wouldn't it be technically possible for someone with enough comp power to predict the proof of work submissions in the short future, at least just sometimes? It wouldn't need to be 100%, just a small edge would be enough to win on the long term.