I'd like to design my own pen-and-paper fantasy RPG, but I'm not sure what to do or how to handle it, so I need advice. Is there a list somewhere on the Web of game mechanics for various systems? I don't want to re-invent the wheel. My hope is to create a game which will allow D&D/Planescape players and DMs to use the material they already have in my system (obviously, I cannot use copyrighted named monsters or races like Bauriar or Beholders, but I'd like to have a relatively simple build system that would let such things be added to the game with a minimum of effort. I'm not trying to recreate D&D exactly, but want it to be possible to play those kinds of games using my system.
I also want to include stuff that isn't already in D&D or other games. Does anybody have a "wish list" of classes/jobs that aren't in current games but you wish they were? Or anything else you might want to see in a game? Things that you love/hate in a game system? I also want to avoid having 20+ books for the system, as in D&D; players and DMs shouldn't have to shell out that much money for a COMPLETE game system (Frankly, I'm sick of it.)
Any advice, criticism or comments are welcome!
I'm actually interested in what's on *your* wish list. I've enjoyed doing some design within the bounds of a system but will admit that actually developing a system has never pulled me in. So I'm curious what inspired this for you, for starters.
And in any case, I suspect that you might find The Kobold Guide to Game Design a useful resource.