I hate to break it to you, but with few exceptions any popular website that allows users to upload their own content will have porn on it. Even YouTube Kids has content that is inappropriate for children.
If you do not want you game to be available on the same website where there is porn available, tbh I think your only options are to either 1. Work with a game website that has a thorough approval process (e.g. Cool Math Games) or 2. Create your own website for your game.