There has been quite a bit of talk online for the past few years in the world of RPGs ever since The Forge posted about this same topic. This topic about RPG systems and how they actually set the tone for the games to be played. I would like to add to their article and comment on few other things that it covers.
One thing that system sets that people mostly seem to fail to realize is tone. Some systems do this well, others tend to do it rather poorly. Some people feel that Tone and Setting are the same thing but I disagree. A setting is the surroundings of where the game takes place, what the characters interact with and knowledge they may have. Tone is the overall emotion state the players receive when at the table.
A system can have a detailed, in depth setting but still fail to deliver tone. Generally these are games that tend to be more of a generic gaming engine than a story engine. An example is White Wolf's World of Darkness. While the setting details can be thick, backgrounds are beautifully articulated and well versed with everything you need to make your own world up it fails to deliver the tone in it's rules.
The game WOD states it is a story driven game yet the players have very little control over the direction of story. Sadly, the game play is very much like the traditional game style with a Storyteller hiding behind a screen, rolling dice and keeping secrets having all the sole responsibility for 'world' development. The rules themselves do not allow players to drive the story but rather be much like a pawn in the story the ST has already designed. The virtue and vices are weak player drives with too much vagueness. I doubt many people will be excited about being overly slothful. People will say that is depends upon the ST and that is true, most story based ST will probably alter the rules to make it work for their group but perhaps this is just because the rules were not defined enough to start with. Sorry Eddy Webb! I still <3 your blog! :D
Tone is important to make the player feel that gut feeling of excitement about what is happening. Games that do this are less flexible with the rules and are more focused on the a certain defined basis. Those that have that focus normally add the drive by adding limitations and making the player be creative to overcome them. These games do not use the Rule Zero of D&D and allow the players control of the scene and take over some of the former GM's controls. Doing this allows all the players to add into the game and not just things that come from the GM's mind. 3 or 5 heads are better then one, and I can say a story can be made matter the more people that are allowed to alter the setting and set their tone for themselves.
GNS Theory (Gamist, Narrativist, Simulationist) is another topic The Forge had posted after taking the time to research how gamers enjoy RPG's. Based on what you enjoy doing, there might be a better system to fit your needs.
The Gamist tend to enjoy games that give a challenge that has a clear path. This can be getting an item, slaying the monsters or getting the highest number. Games that tend to this well are traditional games like
AD&D, Warhammer, Shadowrun, or Rifts.
The Narrativist likes to have control over the scene and be about their character placing spotlight down upon them as the character. This allows them to focus upon moral dilemmas or open concepts called Bangs, that doesn't always have one answer and sometimes all the answers might feel wrong. Some games that are driven like this are Sorcerer, Dogs in the Vineyard, Apocalypse World, Burning Wheel, and Lady Blackbird.
The Simulationist enjoy involving themselves in the game and making decisions on what they would do rather then what the character would do. Sometimes these players are mixed up with Narrativist due to the similar behaviors at the table. The biggest difference of the two is the way they drive the story. Simulationist like to have complete control of what their character can do and will not allow rules to interfere with their in-game behaviors. A Narrativist will accept a mechanic that will allow a decision to be made to evolve the story ahead, like Duel of Wits. Games like GURPS and the Palladium systems best carter toward this type of game play with very open rules for creation and very little to no social mechanics.
Most people play a bit of a mix but are dominantly one or the other much like some other games.
Gamist-Simulationist mix: D&D 3.5, Pathfinder, Battletech/Mechwarrior, Modern D20.
Gamist-Narritivist: Mouse Guard, Legend of the Five Rings, Burning Empires.
Narritivist-Simulationist: World of Darkness.
So saying system doesn't matter cannot be true because each system has a game style it caters too. So if you are bored with your current system, try another one in a different focus. Perhaps that will light the fires of RPG passions back into those game nights.