dead said:
All these RPGs deserve their OWN system because, like it or not, a system is never “invisible” -- it colours the campaign world itself.
There are two types of systems in my experience: generic systems which are (or at least, try to be) invisible and don't have any particular influence on game play, and idiosyncratic systems which are specifically designed to be noticed by the players and provide flavor to the game. Personally, I generally tend not to like the latter variety, since most idiosyncratic systems tend not to be particularly simple or consistent.
D&D is big swords and big spells, it is hit points being sloughed off in waves by fire, acid and lightning. It is not a system that lends itself well to science fiction, nor is it a generic system
Agreed, -D&D- is all of those things. D20 is not. Want a game where PCs don't get better during the course of the campaign? Give out things like karma points (used to reroll or modify the results of dice rolls) instead of experience points. Want a game where players don't automatically get better at fighting as they learn new things? I came up with a skill-based combat system for d20 within a month of d20 Cthulhu's release. Want a game where players don't have loads of hit points to slough off? Great, just don't have players increase their hit points as they level up. From my point of view (yours can and obviously does vary), d20 is the simple, flexible, and consistent system (with a large base of players that already understand the basics) that I have been waiting for--roll a d20, add your modifiers, beat the DC. It is much, much easier and less time consuming for me to take this core system and make a few tweaks to achieve the exact results I want than it is for me to thoroughly learn another rules system, persuade my players to try it out, and teach them the system. I have satisfactorily run d20 high fantasy, grim and gritty fantasy, modern horror, hard sci fi, Star Trek, Star Wars, and modern espionage games with mild tweaks to the core system that makes it fit the genre just fine, and in every case the tweaking has taken less time than it would take me to learn another system, and teaching the tweaks to my players has taken an average of 10 minutes because they already know the system itself.
Let me give you a different analogy to sum up my view of diverse rpg systems (versus, say, d20): an rpg system isn't so much a skeleton as it is the core genetic code of a DNA sequence. Just like God, nature, chance, or whatever creative force you believe in has created a huge diversity of body types with DNA sequences that share a huge percentage of identical genetic code, with some new sections of DNA added to account for the individual characteristics of each organism, so I keep the core of the d20 system for all of my games and tweak some sections of the rules to suit the setting or genre.