Post originally by John Kim at 2003-04-22 23:15:57
Converted from Phorums BB System

Actually, the difference of bell-curve makes a significant difference in the effect of modifiers. Harn has linear modifiers to skill rolls, so for example you might take a -10% penalty to your skill rolls from encumbrance. Compare this to a -1 modifier on a 3d6 roll.

The effect is most noticeable on the edges of the system. If you have a 10% chance of success normally, this is roughly 6 or less on 3d6. In a linear system the chance will drop to zero. I believe HarnMaster has a minimum chance of 5%, but this just highlights the problem, because that means the modifiers make no difference. The 3d6 system can represent things becoming progressively more difficult: i.e. even though your chance is 9.3% for a 6 or less, you can still take a -2 penalty and have a small but real chance of succeeding.

As long as chances stay in the middle ranges, the differences aren't too major - but when you start approaching the edges (small and large chances) then bell-curve vs linear makes a big difference.

I have a discussion of this at
http://www.darkshire.org/~jhkim/rpg/systemdesign/dice-methods.html