Looking for some feedback please...
In my humble opinion, modifying attribute/skill dice seems awkward and too severe.
Instead, the target rolls defense dice to oppose the attack roll, which would be more granular and perhaps more intuitive.
Target behind soft cover = D6
Target behind hard cover = D8
Target behind prone = D8
Target at two range steps = D6
Target at three range steps = D8
Target at four range steps = D10
Target at five range steps = D12
Dim light, thin fog/smoke = D8
Darkness, thick fog/smoke = D12
For example, a target on the ground (+D8) behind some foliage (+D6) and three range steps (+D8) away would roll 2D8+1D6 to oppose the attack roll. On average, the defender in this situation would negate about one success from the attack roll.
Any feedback is greatly appreciated.