The science of magic

how does magic work in this universe? Are there laws of physics and limitation? or can everything be explained by "well magic"? believe it or not, there is a scientific explanation on how magic work in this universe (kind of). Their world, like ours, is made of atoms. Those atoms are themselves made of protons, neutrons, and electrons. Where it changes is that there is a fourth particle that I would simply call "mana". This "mana" has many particulars properties.

-Mana can be manipulated by species with a certain amount of intelligence thanks to a part of their brain. (which we, magicless humans don't have D:) 

-Mana can influence other particles by slowing or accelerating atoms (useful for fire or ice spells)

-Mana can mimic the other 3 particles. for example, Mana can mimic electrons to make an electric current or changing an atom charge ( useful for electric based spells) or even an entire atom! 

-Mimicked atoms can be used in chemical reactions (like combustion).

-Mimicked mana will always try to turn back into pure mana, even if it means doing a chemical reaction that cost more energy than it produces ( so "CO2 made out of mana will eventually turn back into O2)

This definition may get updated/enriched if contradiction arises, or I need to specify more for it to do something else.

Creatures of the world

most creatures you would expect from a fantasy world, elves, dwarves, dragons, goblins, kobolds, etc.

Some of those creatures live in communities of different sizes. While orcs are nomads that live in the other's territories based on their prey location, some creatures like humans, dwarves and elves live in huge kingdoms. Every kingdom is always threatened by their neighbors to lose pieces of land and the political situation is a mess. They are generally composed of one big capital, followed by a few trading villages and agricultural villages. You will almost never see a member of another race in the capital of another race kingdom, as the clash of "way of being" are way too important for anyone to be comfortable. (aka, an elf trying to live in a human capital will be like "There are not enough trees here to make my usual prayer to nature"). You will see more diversity in villages that are outside of the capital.