What might the rules be for free content that's released for another service?

^^  If you didn't make it, don't own it, don't have a legal document in which the owners state you have a legal right to re-publish it, you can not do anything with it. We're very big on protecting creators and creators rights. We also generally don't allow free content on our platform as we try to create a culture where artists work are directly and monetarily valued, as this industry is notoriously guilty of undervaluing creators. You are more than welcome, of course, to do anything you'd like for your own private games with your players. It's once you get involved with distribution / re-distribution that these rules apply. Thanks for your great and sincere question!