haha, now I get to explain it all.
The basics of a game, at least in this sense is simple.
There is the game's writer, who makes up stuff for the game. Before the game actually happens, they must write several things
-PC list, the list of all the player-characters in the game.
-Motives, write down all the motives each character has.
- The flow, which is a general idea of how the game SHOULD go.
-character sheets, a description of the character, their past, personality, what they can do, etc.
- The tease, just a short storie to open up the game, possibly provide a prologue, and set the tone of the game.
How does one regulate what players may opr may not do? You don't, really. Once everyone has gotten their character sheets and everyone knows their motives and all relevant backstory and has gotten 'into character', the game just, goes. Everything is improved, and it might wind up following the flow, or it might go in a completely different direction. The bad guys might win, everyone might die, or the heroes survive triumphantly, it really all depends.
The magic system for westfinder is fairly straight forward, but would take too long to describe. For a game like this, the system would be tweaked somewhat. Most of the magc would be what we call "improv magic" Where a characters reaction is based in part on what they know of the spell, and whatever specifics might guide that character (For example, thrusting your hand out and shouting "shower of nails!" at a faerie would elicit either death or extreme pain, then death, while on someone whereing armor, they woudl have the options of a) shruggin it off, b) grunting, then fighting as if in pain, or c) being severely disabled, at least until healed).
note, this is a rather incomplete description, as I don't have much time on my hands. sorry.