Is there a good primer on RP systems?

[katewithcurves]

Clearly it must be because I am a girl (or used to be blonde) but I was somewhat overwhelmed by the gaming systems section of the On/Offs questions.  I played D&D with an ex-boyfriend long ago so I know that dice come in 4,6,8,10,12 and 20 sides.

Since clearly people here write within those settings, is there someplace I can learn about some of the more popular ones out there?

[HairyHeretic]

I'm afraid it's not going to be a one size fits all approach here :). There are hundreds, if not thousands, of RPGs, and each has their own particular mechanics. The d20 one's (D&D) are certainly one of the more common, but by no means the only one out there. I'll see if I can't illustrate a few different basic mechanics.

Percentile - Every is based off a 1-100 roll.  Normally each player will have a set of skills or characteristics, each rated at X%. Roll under (or perhaps over) that skill, and you succeed. If you don't, you fail. This can be futher modified by enviromental circumstances, or players condition or gear, to shift the target number up or down. If you succeeded (or failed) by a certain number, then the result could be better or worse than expected. Games I know that use this would include Fantasy Flights 40k series (Dark Heresy, Rogue Trader and the forthcoming Deathwatch) and Call of Cthulhu.

d10s v Target number - This is commonly seen in White Wolfs systems. Each player has a certain number of dice based on stat, skill, gear and circumstance. Roll all of them, and any dice which is Target Number or higher is a success. Sometimes, a 10 will count as 2 successes, or a 1 will remove a success. The more successes you get, the better you do. Games that would use this would include Old and New World of Darkness, Exalted and Scion.

Shadowrun uses a similar mechanic, except it uses d6s instead of d10s.

d10, roll and keep v Target Number - Slightly different mechanic, same dice. The player has a certain number of d10s, based on stat and skill. They roll them all, keeping a number equal to the stat. These kept dice are counted up, and the result checked against a Target Number. For example, I might roll 6 dice, keep 3 of them (total roll of the 3 dice say 17) and compare that to my target. If I had a Target Number of 15, I would succeed. If it was 20, I would fail. Examples of this would be Legend of the Five Rings or Seventh Sea.

The d20 systems, or at least the ones I am familiar with, roll a d20, add modifiers from your skills, and compare that against a Target Number. Beat the Target and you pass, roll under it and you fail.

A rarer one is roll 2 dice, take the difference between them, add that to a skill, and compare to target number. I'm familiar with this mechanic in Qin and Feng Shui.

To cut a long story short, there are quite a lot of different ways of rolling dice, and they are going to vary from game to game. It's probably better to find a game whose background setting appeals to you, then ask those playing it for an explanation of the mechanics.

[Oniya]

With White Wolf and Shadowrun (unless they've changed the mechanic significantly), your top numbers counted as an automatic success, and then you could re-roll that many dice to attempt to get more successes.  This can, with luck, get into a cascade effect.  I've seen a single die roll cascade into four or five successes (6, 6, 6, 6, 5 - or something like that).

[HairyHeretic]

I didn't want to go into exploding dice since she was new to RPG mechanics in general :)

[MasterMischief]

I believe what Hairy and Oinya have mentioned only speaks to Task Resolution.  There are other aspects of systems that influence how a game plays.  Rules Light vs. Rules Heavy (Crunchy).  Narrative vs. Gamist.  Class Based vs. Point Buy.

Task Resolution: the mechanics used by a system to determine the success or failure of a particular action undertaken.

Rules Light systems attempt to only provide as much framework as is absolutely necessary often leaving ambiguity and more control in the hands of the GM and, more rarely, in the hands of the players.  Rules Light systems are often less concerned with the damaging capacity of weapons and lump them in broad categories.  For example, they may classify pistols as light, medium and heavy instead of defining the differences between a 38 calibur and a 45 calibur.

Rules Heavy systems attempt to provide a more comprehensive framework and account for more possibilities.  They are frequently more concerned with details and as contrast to the example above, would specify the details of a 38 versus that of a 45.

Narrative focused games are more concerned with story line.  Plot and drama are seen as more important than combat.

Gamist systems are more focused on the 'game' aspect of role playing games.  Randomness and balance are often seen as important as well as some measured 'victory'.

Class Based systems present premade templates that identify the abilities of a commonly recognized archtype.  For example a 'Fighter' will have a list of abilities all fighters should have.

Point Buy systems assign costs to abilities and allow the players to decide which abilities their characters will have withing guidelines often set by the rules themselves or the GM.

I am afraid this just scratches the surface.

[Lithos]

Also with more complex game systems comes the unfortunate side effect of needing tons and tons of tables to roll the dice against. I would strongly recommend a system where tables are kept minimal, system such as role master for first system game would be quite brutal. Personally, I think that narrative games are the most fertile ground for the kind of playing one would expect to do here.

[Beguile's Mistress]

You might want to also take a look at Lord Drakes's "So... what is a System RP Game??" for some helpful information.