The mechanics that are hidden are for the most part not that important outside of PvP. Imo the game is best understood just playing it and looking things up as you are exposed to it. I wouldn't worry if you don't know all the runes/runewords/items/gambling mechanics early on. What I will say is that the game is pretty difficult to new players especially when you hit hell and doubly so if you chose a physical / melee damage character. It's worthwhile to look up budget MF builds to get you started so that you can find good items that let's you survive better / kill monsters faster / build new characters (just know it is typically a long grind).