governing the mechanical
aspects of an RPG
. Specifically, an RPG System
tells all persons, whether they be players
or game masters
, involved in the game what to do and when to do it. Such as the exact method of resolving combat, which usually involves the rolling
. Or the creation
of a character
for the given game setting
. Or the acquisition and use of skills
Most RPG Systems differ at least slightly, unless one is specifically modelled on another. For example the FUZION system is actually modelled on Interlock by R.Talsorian Games. Other RPG Systems are not at all similar, such as D20, Palladium and FUZION.
There is one simple common thread that ALL RPG Systems share: Role-Playing. All RPG Systems try to take role-playing into account. Most RPG Systems try to encourage role-playing, but no amount of rewarding can create a good role-player. An RPG System can include random roll elements to encourage good and varied role-playing, but that doesn't mean a poor role-player isn't going play a stereotype instead of a unique character regardless. So despite any RPG System's noble attempt, it's up to each individual player to actually role-play or at least try to.
Some example RPG Systems:
The Palladium system by Kevin Siembeida
Unisystem by CJ Carella
FUZION by R Talsorian Games and Hero Games
D20 by WOTC
D&D by TSR
AD&D 2E by TSR
Amber, a diceless system by Eric Wujcik
And many many others.