Had a couple of new ideas on this topic:
First one is about types of defenses: IMHO the 4 defenses should cover a range of situations as broad as possible, to avoid having to add additional mechanics to handle specific cases. Something like this:
- Dexterity DB [basic value based on Qu/Ag]: used not only to dodge blows but also in all situations related to dexterity/coordination
- Stamina DB [St/Co]: used to resist fatigue, diseases etc, but also in opposed strenght checks and similar situations.
- Mental DB [Re/SD]: used to simulate force of will, but also to avoid deception, etc
- Magical DB [Pr/In?]: used to resist all kind of magic
Armor should be counted separately and could be added as a bonus to any DB, depending on situation (for example it could be added to dexterity to avoid a blow, or even to Stamina to resist the effects of an acid attack, and so on...).
Still unsure if DBs could be developed as skills, but leaning toward no.
Second idea is on how the whole thing could actually work. I'll try to explain it with an example:
Character A is trying to sneak past Character B, who is guarding the entrance of a building.
So A uses his Sneaking skill as OB agains B Mental DB (as he's trying to deceive him, "attacking" his senses).
OTOH B uses his Perception skill as a OB, against A Dexterity DB (as sneaking is a dexterity-related task).
Both may use their OB skill to "parry", shifting it to increase their DB.
In the character A case, "parrying" would mean that he's concentrating more on not being seen by B than on passing past him, while going on full offensive would mean that he'll try to pass through B no matter what, even if it means that he'll be spotted in the process.
In character B case "parrying" would mean that he's concentrating in guarding his spot, in making difficult for anyone to sneak past him. Using all his OB to "attack", OTOH, would mean that he's actively seeking for A, maybe even leaving his spot for a while to go out and seek him.
Results could be:
- A "hits" B (manage to roll high enough to surpass B defenses): means that A sneak past B, accomplishing his goal.
- B "hits" A: B spots A and prevent him to sneak past him.
- Neither of them "hit" the other: B doesn't spot A, but A isn't able to sneak past him.
- Both "hit": A succeed in surpassing B, but is spotted (so B can pursue him, call other guards, etc)
Additionally, to make things more interesting, both could use "maneuvers" instead of just attacking, to gain an advantage by changing the situation.
For example A could try to "feint" to lower B defenses (by throwing a rock against a distant wall to distract B).
Or B could try to "disarm" A, using a lamp to remove bonuses granted by darkness...
Thought/impressions?