Mana

The idea behind the mana system in this game is similar to how stamina works in real life. If you were athletic, you could hold a water bottle in your hand all day without an issue. However, if you decided to carry 5 gallons of water, then maybe you could only hold it for an hour before getting tired. That is because holding all that weight uses up more of your athletic capacity, and so depletes your stamina faster. But, if you did this every day for a year, then maybe you could get to the point of also being able to hold 5 gallons of water for a whole day without issue, only starting to run into problems when it becomes 10 gallons instead. 

The idea here is doing tasks that don't use a lot of capacity doesn't deplete your energy as much, even in rapid succession or prolonged periods of time. But, doing something that is close to your limit will bring your energy down much quicker. And, if the capacity increases so that the previous task that was near the limit now becomes easy, then it won't deplete as much energy since the task is no longer difficult.

The analogies and tutorials for how mana works will be improved upon as I start testing with people and figuring out the best way to phrase this, so please be patient with me if this doesn't make sense yet.

Also using mana to cast spells is not going to be required to enjoy the game. This is more akin to redstone in Minecraft to how it interacts with the world.

Formulas

The mana system is very unique, but the document is located on a separate computer so the formulas will not be added here just yet.