The entire world is one strip of beach, endless sea on one side and an endless amount of bramble growth on the other. People live their lives on strips of beach which range from anywhere between 2 to 5 meters to 15-20, and if the area has been cut out further this might extend to up to 50+ meters
3 schools of magic + 1 basic state
Flow is a meditative process by which you understand the ways in which the natural force that is called magic functions. Not terribly useful on its own, its meditative so it could be used to calm you down but it doesn't confer any special abilities. It is a pathway to understanding how to use any of the other schools, and you become faster and better at using magic the more you are adept at Flow.
Anima is the manipulation of water or sand. This is the easiest and most useful school to learn for the average person, therefore almost anyone you encounter will have some knowledge of this school. It is used by the average population to build homes; manipulating the sand into place and packing it into place with manipulated water. Most people will use this for temporary shelter, building something small to last the night out in relative comfort. More skilled users can build structures that last for days or even weeks before they need to be readjusted. Other creative uses might involve splashing water in an enemies face to distract them or moving the sand beneath their feet to throw them off balance. A particularly gruesome use, but extremely technical and would require many years of training to access would be to form a fast moving pillar of sand towards and enemy, then to manipulate water through the construct so it becomes solid and then impaling your enemy.
Manipulation of the brambles that form one edge of the line that civilisation lives along and metal, which is found deep beneath the sand. Most people will have a working knowledge of this school as well, but it would almost never be used for metal, as most average people would never even see or interact with it in their lives. The brambles have grown incredibly dense, impossible to cut through with an axe, but can be manipulated to grow in certain ways or to die along certain branches. This is according to the brambles flow state, which must be gauged by the Materia user. Most people are capable of snipping off bits, which they would use after drying out in the sun as a very potent fire source. Skilled users can make it grow, forming additional walls where needed. It can also be slowly trimmed away en-masse, which some large settlements have done, but the further in they cut the thicker the brambles get and the more time and energy is required to dig more space.
Metal is incredibly rare, requiring tremendous amounts of time and energy to dig with Anima beneath the sand for chunks. Although possible to forge in a traditional way, skilled practioners of Materia can forge without fire, turning the chunks to liquid at their fingertips and bringing the pieces together. Again, this is according to the flow state of the object, and the better and more in tune you are with the flow state of the metal you are working with the stronger and better the final product will be. Most people fight with bramble weapons because metal is found in such small amount that it is almost always used for small ornaments. However, sometimes enough metal is harvested that blades and other weapons or armour are forged, and the people who use them become borderline unstoppable. Imagine fighting in World War 2 with an Ahbrams tank, still very much defeatable just incredibly difficult to do so and therefore an incredible advantage against your opponents.
Materia manipulation is almost never used in direct combat, as its typically a time consuming process. However, there are certain techniques which are possible. A skilled practioner could somehow grab his opponents wooden weapon and instantly shatter it by pulling against the flow state.
The rarest and most mysterious form of magic is Eclipsis: the manipulation of the sun and moon. This incredibly esoteric and powerful magic requires deep thinkers and people with strange and warped worldviews to access, as its incredibly abstract in nature compared to the use of Anima and Materia. The average person would probably not even know that this kind of magic existed, or would tell of it in the sense of old legends. There are practioners in the current timeline but they are far and few between. The most showy and bombastic magic is found in this school, being able to absorb solar and lunar energy during the day and night and use it in various ways.
The solar options include shooting beams of fire, causing objects or people to spontenously combust, heating an object, person or area up and many more which mostly include fire and heat. The lunar options include beams of ice, freezing an object, area or person, freezing large patches of water.
These are the basic options, further study and abstract thought can reveal more interesting effects, including but not limited to: using lunar energy to instantly affect the tide in the area you are in, combining both types of energy to cause pure darkness in an area (like an eclipse) or even, with a lifetime of study under your belt, using solar energy to bring the dead back to life. meditating in a flow state at either night or day will cause you to take in energy of the particular type, which is expended upon casting spells and when you run out you will find it impossible to cast spells until you flow state again.