One of the problems new users have is aiming too high with their ideas. Learn to walk before you can run. Complete tutorials that are not specifically what you want, but will help you learn how GML/DnD works. After you've spent a lot of time doing this, the steps to create your own dream game will be a lot clearer, and you will start to visulise how you can use the tools to build what you need.
I've used GMS for years, and even for me, the concept of building a game like you've described, would require extensive knowledge and work. Start small, and work your way up.