Hello,
I see you post an interesting project, when I read the job details, I see some challenges on your project.
I will build the platform using WordPress, for that quiz system I will not use any plugin, I will use php programing, the complete website will be fully editable, you will able to add any question or story anytime , or you can remove or delete these quiz whatever you want.
For that types of project, need discussion and provide idea.
If you are really interested to build that types of website, please write more on private massage.
Regards,
Moshiur