You refer to a ruleset occasionally. I'm not sure what the ruleset is?
Ruleset is the framework of the game. The mechanical aspect of how the world works, what an entity is and how it interacts. To give you an example, I'll analyze what character means in two different rulesets.
In DnD, a Character is a combination of Level, Attributes/BAB/Saves, Feats, Race, Class, Skills and Gender.
Level is the relative power of a character. It increases by doing activities in the game and works as a platform for the acquisition of the other statistics.
Attributes, Base Attack Bonus and Saves dictate the physical and mental capacity of the character and his combat effectiveness.
Feats modify the behavior of a character in the battlespace and in the usage of skills, weapons and spells.
Race is a feat that dictates the visual representation and the size of the character and how it interacts with classes. Also adds unique modifiers to differentiate the character from the others.
Class is a modifier that dictates what bonus each new level gained will provide and what spells a character can access.
Skills dictate the aptitude of the character when he performs actions in the world.
Gender is visual representation and interaction with the world.
In Dragon Age 2, a character is a combination of Level, Attributes, Race, Class and Gender
Level is the relative power of the character. Each level gives points that can be spent to acquire abilities and attributes.
Attributes dictate the combat effectiveness of the character
Race and Gender the visual and auditory representation and interaction with the world.
Class dictates the access to abilities that can be bought with points from leveling and interaction with the world. Also they modify the bonus he gets from attributes.
So if you say that you want to play Dragon Age 2 with DnD ruleset, you will have to transpose the character.