GMMichael
Guide of Modos
I picked Roll High for Modos RPG to follow a design theme: higher is better. Contest results, skill points, damage rolls, die type, hero points, power levels, casting difficulty* - the higher, the better. So, it's a consistency thing.
Roll Under would have the apparent advantage of simplicity: there's no need for an attribute bonus with Roll Under, because the attribute score IS the bonus. However, for Modos RPG anyway, contests (outcome quality rolls) are a comparison of the PC's result and the GM's result. Which, with Roll Under, would mean that the GM would need an "attribute" score to roll under as well. And that becomes a swingy mess with considerations like: did both sides roll under, what if only one side rolls under but still beats the opposing roll, and where does a bonus go if both sides have a roll and an attribute?
*Casting difficulty is a penalty to a caster's contest, which doesn't fit all definitions of "better." However, the effects of a power with higher casting difficulty are better than those with a lower casting difficulty. So, a power with a high casting difficulty is a better power . . . if you can cast it well.
Roll Under would have the apparent advantage of simplicity: there's no need for an attribute bonus with Roll Under, because the attribute score IS the bonus. However, for Modos RPG anyway, contests (outcome quality rolls) are a comparison of the PC's result and the GM's result. Which, with Roll Under, would mean that the GM would need an "attribute" score to roll under as well. And that becomes a swingy mess with considerations like: did both sides roll under, what if only one side rolls under but still beats the opposing roll, and where does a bonus go if both sides have a roll and an attribute?
*Casting difficulty is a penalty to a caster's contest, which doesn't fit all definitions of "better." However, the effects of a power with higher casting difficulty are better than those with a lower casting difficulty. So, a power with a high casting difficulty is a better power . . . if you can cast it well.