Okay, gotcha. I think it's certainly possible to offer an alternative to WoD and other urban fantasy games. I think the challenge is that WoD is established, and so it has a trove of already established lore on which to draw, and multiple games that all tie into the one setting. So they're well established, for sure, and have an existing fanbase and so on.
But....they started off with one book. I think any competition would likely have to do the same. Make one book with a solid foundation upon which you can build.....hint at a larger picture here and there, but mostly focus on what you want that one book to be. If that one book/setting is interesting enough, people will notice. And then you can expand from there.
So I think the key is to establish that foundation first....that entry to the setting....but leave room to expand into other interesting areas or related concepts.
The general concept you have of a modern world mirrored by a hidden, magical world is a solid start. To use what you've offered as an example, I would focus on establishing Midgard and its inhabitants and nations and factions and how they interact with the people of Earth....that would be the first step. That's the core you need to start with, the foundation you build upon.
Then, you can come up with another world that is connected to Earth and/or Midgard and then expand into that world. And then another, and so on, as needed and desired.