Onepapel website is not working for me, so only thing I could check out is your github page.
We already have one bitcointalk community project that is provably fair, and made by our member bitmover.
Name of this project is Bitcointalk Giveaway Manager, it is free to use, and it is all based on bitcoin blocks.
Many people use this for selecting giveaway winners, and you can check it out and compare it with your service:
https://bitcoindata.science/giveaway-manager/Onepapel didnt open here as well.
I would like to see how they are monetizing this kind of tool. But as I can see, looks like they hold the funds until the draw
Maybe I can offer a similar service. Hold funds and automatically send after the results. I dont know if anyone would use it..