Skill20: Margin of Success
A recent idea I had was to eliminate damage bonuses. As it stands, characters get a damage bonus with weapons equal half their skill rank, plus the appropriate stat bonus. Whether you hit dead even or by 10, the damage is the same. Then it occurred to me that in some other systems I use, the more you hit by, the more damage you do and I pondered how to incorporate that into Skill20.
Effectively a bonus to hit would be a bonus to damage. Likewise, even if a defensive action didn't keep you from getting hit, it would reduce the damage. Separate critical rules wouldn't be needed, as the damage of such an accurate hit would be reflected in the margin damage.
This would mean that fights against evenly matched opponents could take longer, as the margin on both sides would likely be small, while fights against goons (cannon fodder opponents) would probably be skewed more in favor of the PCs. The danger would be big-bads, like dragons and giants, I'll have to monitor their damage output carefully in playtest.
I'll also have to tweak some damage dealing spells. Instead of scaling dice of damage, I'm thinking a flat die amount for the spell plus margin. So instead of a fireball doing 1d6 per rank, up to 10d6, it would do 5d6 plus margin. Each +3.5 of margin is equivalent to a d6. Some more crunch to chew on during playtesting. It might slightly nerf magic damage output, which isn't necessarily a bad thing, but a wizard-type could still clear a room of 15 hp goblins.