Hello, I mean this well. As I do find the idea of a riordanverse campaign intriguing. Though finding a suitable GM for this sort of campaign is rather unlikely. I could be proved entirely wrong on this matter. However, the major problems I can see is. First off you've left it a bit too vague.. In quite a well fleshed out setting. This world has been so well constructed by the author over a course of so many books. That asking for a GM without really giving context as to the time period in correlation to the plots of the books is a bit demanding. Minimizing it to just camp half-blood does help some if you are deciding to solely focus on the greek aspects of his universe. Though if you are leaving it open to the Riordanverse then a GM has to find a way to manage all the various pantheons. All the various types of creatures, etc.. Etc.. Which leads into point 2. Trying to get the game mechanics would be a nightmare. Just trying to properly flesh out a system for the powers, and equipment would take a long time planning. Especially if you add more than just what greek/roman demigods can do and the weapons they have access to. Lastly.. I know your kind of thinking. Well.. That's what a GM is suppose to do anyways, so why is that a problem? Well.. The main problem is. It is one thing for a GM to craft a world from scratch. As they can more easily define the limitations and lore of their world. Without much criticism to how they design their world. It is another matter. When they have to craft a system from scratch, for a world which has been fleshed out through an entire series of books. As they have to take someone else's work.. And then try to convert it to something which is functional in a tabletop environment... And not only does that add a tremendous amount of time. That tends to lead to a lot of risk of players challenging the GMs decision for things. It would be another thing if the world was already fleshed out into a functional and recognizable tabletop system. Which then the most the GM has to do. Is familiarize themselves with that system and set a plot within it and go from there. You can look at the dresden files tabletop RPG as a reference towards what I mean.. So, while I think it is a great idea, my suggestion would be. Take time with your players.. To get to where you are all in agreement of the setting within the universe (is it taking place in book 1 of Percy Jackson and the Olympians, Is it a prequel to that. Does it come after the events of The Heroes of Olympus series, during the trials of Apollo?..? Afterwards.. Going off assumptions to what the series conclusion is. Etc.. , what areas of the lore you want to focus on, solely camp half-blood, do you include the kane chronicles or Magnus Chase series... Etc.. Etc... Then when you have the details fleshed out.. Then you pitch out a new ad where you can explain what the nature of your campaign is, and what you guys are needing in regards to a GM. I hope this helps, William M.