I was under the impression that all the worlds in Yooka-Laylee take place within giant books (Grand Tomes, i believe) which is why it makes sense that you can use pagies to expand them. All of these books are about to be converted into pure profit by Capital B himself.
With that in mind, it seems weird that there would be a book about Capital B's own casino, especially considering that this book is also about to be destroyed for the sake of profit. Why would Capital B destroy his own book? In the trailer, Capital B also talks about the casino as if it's a real place in that world.
It's possible that this world will be unique, and that it will NOT be accessed through one of the Grand Tomes. If that's the case, will it still be expandable with pagies, even though the world isn't a book?
Could this be a plot-hole, or something that will be explained during the game?