Although recently I've been using some commercial game systems (GURPS, Hero) I have a tendency to prefer to create my own game systems. This can be considered a bit weird or odd by some folks, and even put others off, since it means having to learn a new system to game with me.
The thing is, I've played a lot of systems, GMed and read a lot more. Generally I find that most game systems have in recent years been heavily design by committee, or are the work of one person and have a very very narrow focus (most indie games do this).
My problem is that some systems don't do well when you sit down and try to adapt them to specific settings, or fail to fill certain styles. GURPS is good for gritty historical, but falls on it's face for heroic/superheroic gaming. It can work for intrigue on some levels, but only if you keep the violence level low, as the survival rate of characters shrinks rapidly in combat. GURPS can be trimmed, without collapsing it, to a more streamlined approach, but you need to know what to trim to make it fit your style, setting etc.
Hero is great for superheroic, and anime in most cases. It does reality poorly though, and does 'normal humans' ridiculously badly. Additionally it does not deal well with a game where economics is supposed to be an incentive - it's money/resources system is broken for the most part. It is also very hard to modify without damaging it... everything is so carefully knife-edged balance, you need to include every power and nearly all the rules (there are a few small ones you can trim but not many)or the character's quickly become so out of whack with each other that it's not funny. And you as GM really do need to understand how each power and each option works before you let a player play the character they have designed... otherwise you'll end up with planet destroyers...
When I design a system it gives me an advantage I often need. I can make sure that the mechanics fit the setting/style and concept that we are aiming for in the game. I can also make sure that I will understand how every part works without constantly referencing a manual And finally I can be sure that the rules will not be filled with lots of extras that get in the way of a story, prevent too wide a range of character differential or introduce concepts that don't fit the setting and desired style for what I am trying to present/emulate/create.
When I use an off the shelf system and modify it, players often balk. Even if my reasons perfectly fit the setting I'll have the "Why can't I have a flying spell? Why Can't I have an automatic weapon in Napoleon's Era?" and the inevitable "But the rules say I can take Submarine pilot/Super Hypnotism/Trained By A Master Ninja, why can't I?" or the downright silly "Autofire Cumulative X8 Quadruple Knockback Armor Piercing Hand Attack via My Gauntlet Of Pain, which if it hits then sets off my 3d6 NND Knockout Poison Energy Blast which can only be stopped by a forcefield".
I design for a certain level of simplicity on many levels. And if I leave ambiguity someplace (such as a magic system) I leave in the GM Veto power in the design (which when clearly spelled out in black and white tends to be accepted a lot more in a system I designed than one I bought off the shelf with many players... like the book must be the authority and anything not specifically listed as unavailable must be possible in their minds).
Tags: Game Design Homebrew Vs Commercial
