Well, a huge part of game design is presenting the world in a way that does not break your immersion. You can constantly have pop ups that explain everything about the world, or you can experience it in a realistic situation.
You might have a prologue where you start walking down a corridor. As you walk further and further, you notice a skeleton standing in the middle of the hallway. At that point, there are two game decisions.
Option 1 (Not suited for SG in my opinion): As soon as you get close enough to the enemy, a pop up appears telling you that skeletons can be defeated, but will resurrect and reassemble themselves after some time.
Option 2 (Probably better suited): As soon as the enemy is in sight, it walks into a trap. maybe it's a boulder that smashes him to pieces, or a dart shooter from the walls that causes him to fall apart. However, before you can reach him, he's started reassembling himself.
The second option teaches you game mechanics by example without really ruining the immersion. Books can do the same thing. In a dungeon, you might be forced through a room where someone is sitting at a table far away from you with their back towards you. At another table, right where you enter the room, there's a bow and quiver leaning against a wooden chair, and a book on the table. You read the book and it tells you that bows are a very useful weapon for picking off enemies from a distance. As soon as you can see the enemy that is sitting at the table, a small overlay appears, telling you which buttons to press to operate the bow.
Having pop-up hints explain the game to you often causes you to lose immersion, because they're always written like the developer is explaining mechanics from an outside perspective.
Here is a comparison between two ways of formulating a hint:
Option 1 (Pop-up Hint):
"Bows are ranged weapons, used to take on enemies from afar. Arrows fired from a bow can cause enemies to be crippled, making them partially immobile and thus rendering them incapacitated. Use your bow on the enemy across the room."
Option 2 (Book on table):
"Today Maryck returned wounded from a raid. They had found a small hunting cabin by the river, and approached with care. However, out there by the cabin somewhere, a hunter had heard them approach from afar. Maryck was too careless and was shot with an arrow. Luckily, it had hit him in the thigh. He could've been off a lot worse if the hunter had the chance to fire another arrow."
I personally think, and I hope you all agree with me, that the first option breaks immersion too much. What would be fine is giving your some sort of tip on the controls.
Also, if there were to be libraries in the game, I would like to sign up as a writer. The additional lore in The Elder Scrolls has always amazed me, and I think it adds a whole new level of excitement and realism to a game.
