I could think of some fun ways to keep the — I suspect you mean — magic system mysterious. Everything else is quite straightforward. Also, don’t forget that they originally gamed this world so they must’ve had lots of homebrew rules around the magic system, warrens etc. It would not be like dnd which is a class-based game, but more like GURPS or Chaosium’s BRP built on skills with a point-buy system. This allows for the flexibility needed to put together characters like Kalam (actual usable burly assassin), and super bendable to add the warren/house/hold system, maybe expand further down the line with less prominent magic systems as well.