Creating a world isn't always easy, there are a lot of rules one needs to come up with, its normally easier to import existing worlds and use those rules. As for me I just made it so that multiple fantasy countries exist on my world. That way people can use powers that they like from movies, books, tv shows, and video games, as long as the dm says its alright and makes sure to balance everything, no invincibility for anyone. I mention some of this at the top of the homepage. If you want a world map you can have one but I prefer to leave my world full of mystery.
Also note, for maps while playing the game I like to have all my players persist their cards, figurines, and player mats, then I load maps of the workshop. That being said I like to personally thank everyone who has made maps on the steam tabletop simulator workshop, thank you guys so much for these, for they helped breath life into the world and it was really fun having my players break things like in an anime. also to anyone who made models or effects on the workshop.
For my game there are also 7 primary elements and several secondary elements. Each element has its own strengths and weakness. The base ones are Fire, Earth, Lightening, Nature, Wind, Water, & Mind. After that you have Ice, Soul, Life, Death, Blood, Time, Sound, Light, Dark, Void, Nothing, Force, Gravity, Ki, Arcane, Enchantment, Angelic, Demonic, Dragon, God. I also have an abundance of races and creatures which will be covered in the races and species list, it can get strange. So what it boils down to is that my world is a bunch of other worlds mashed together.