in D&D, targets have a set defense, typically known as AC (Armor Class). The attack roll, usually a d20, attempts to
meet or exceed that AC. In old school, basic D&D, you had to meet or get below the AC, if I remember correctly...
because the AC's ran from high to low, starting at 10 and running to as much as -2 or -3.
I've actually considered attempting to do something like this with HQ...in fact, I was going to do an attack value
and a defense value for all monsters and traps, and the heroes would be the only ones rolling. It would make things
a little clearer for the combat, and speed things up by eliminating some of the rolls needed.
I found it difficult to make it work, however. It would require some serious analysis to make things balance out
so that the only thing you were changing were the monster statistics.